I'm not sure if it is better to post here or on the medical boards, so if it is in the wrong place, please feel free to move it.
There are some things about DS that I find to not be quite "normal" and I am looking for some fresh eyes to see if anyone has some thoughts that could help me, or some new ideas. I'm not sure where to start, so sorry if this is a bit muddled. Knowing myself, this is likely to be long, so sorry for that.
DS is going to be 17 months in about a week.
Some background - He has reflux, and was medicated (Rantidine) until about 7 or 8 months ago, when he was weaned off. He was also on lactulose to help with constipation. At around 3 months old he had a barium x-ray and ultrasound done on his stomach, and all looked normal at that time. Currently he is teething eye teeth and molars (

), which have been coming in for awhile. 3 are just cutting through the gums, some are most of the way through, and some are still moving in the gums. I have been giving Tylenol at every sleep time, and sometimes camilia, but have been avoiding Motrin and Advil for the last few weeks. The Motrin and Advil seemed to work and help sometimes, and others they seemed to just hurt his stomach and make things worse, so I stopped giving them. I am assuming it is because of the teething, but he is in a reflux flare. It happened with incisors as well. Even though he was medicated, the reflux seemed to get worse for awhile. At around 13 months, he was diagnosed as MPI by a blood test. They also tested for soy, egg whites, fish, and I can't remember what else, if anything. All of those came back as negative. The blood test came back as him just barely being over the line for it to register as a milk protein intolerance. However, at the time of the blood test he was often having only 4-8oz of milk formula a day, so I'm not sure if that would affect the outcome of the test.
He has some eczema. Not very bad, really only on his cheeks. I have been putting lotion on 5 or 6 times a day for months, and it has improved quite a bit, but is not completely gone.
There seems to be a constant, very tiny diaper rash. I always use diaper creams, but it doesn't ever go completely away.
He always has a tiny bit of mucus in his nose. Very little, but it is constantly there.
He will not drink very much. By this I mean he will have 12-18oz of soy formula a day, and if it is a good day, 1 oz of water. So that adds up to between about 12-19 oz of total fluids a day, and for his weight I think he needs to be around the 40 oz mark. I mentioned this to his paed, and was told that the lack of wet diapers and dark yellow urine are a bit concerning, as it is hard on his kidneys, and to try to get him to drink more. (Because I had only been trying for months to do that

) I have tried giving him different flavours of rice milk, diluted juice (both results in him spitting them back out and giving me a dirty look), calling out to him and showing him every single time I take a drink of anything, making a game of it and clapping and cheering each time he takes a drink, trying different sippys, open cups and straw cups, and me drinking from a sippy cup. None of this has helped increase his consumption. Because he has such a low fluid intake, I was told to keep him on purees, so at almost 17 months, I am still spoon feeding him purees.

When he does drink from an open cup or sippy, he often gags and coughs. So he is still on a bottle for both of his milk feeds, as that seems to be about the only way he can drink without gagging.
DS is an extremely slow eater/drinker. Most meals take about 45 minutes, a bit of which is because he gets so distracted and likes to talk about everything. And it still takes him about half an hour to have his bottle.
He is always constipated, which I am attributing to the low fluid intake, but it could also be partially because of something else.
His breath is always quite bad, again I am assuming because he does not drink much.
He constantly has bags under his eyes, which could be from lack of sleep (see below)
He has a very hard time falling asleep, and staying asleep. There are some nights it takes him 4.5 hours to fall asleep at bedtime, other nights only half and hour. He has not slept through the night since he was 3 months old. An average night for us is multiple NWs, 1 or 2 he puts himself back to sleep, some I am in and out in 15 or 30 min, and a couple are at least an hour long. Usually at least once or twice a week we have a NW that is 3 to 4.5 hours long. He will have periods where we will have a few good nights with 2-4 NWs, and he will put himself back to sleep every time, then a bad patch for a few nights. Or sometimes he will alternate 1 good night and 1 bad. He is APed to sleep. Until about 4 months old he was put down independently, or I would pat his bum or rub his back if he needed help. The sleep got worse and worse so that around 7 months he was always APed. He was rocked to sleep for a long time, and now he is held until he is drowsy, then put in his crib. I am mentioning the AP last because a lot of people seem to hear about the AP and then stop listening. I understand the reasoning there, but the AP started because he was taking hours to fall asleep and having so many NWs that were so long, and the AP was our way of coping. His paed was very willing to help until he heard about the AP and since then has basically told us to get our LO more attached to his lovey, and we may have to try the Ferber method down the road.
I tend to have 3 different thoughts. One is that he has something in the back of his mouth or throat that is not quite formed correctly, which is why he is so uncomfortable drinking and gags so often.
Another is that he has another intolerance or sensitivity that has not yet been found. I have gone over his sleep and food logs to find a correlation, but have not found anything. Salicylates were mentioned to me on another thread, so I need to look into that a bit more.
And the last is that the AP is to blame for the sleep, even though it started after the bad sleep, and the rest of it is normal.
We have an appointment with the paed in the middle of May. I am someone who tends to go in and tell the doctor what is going on, then listen to his advice, agree and go home. Then I get home and think, no the doctor is wrong and not the one dealing with this every single day.

So I need a plan of action for our next appoint. I'm not sure if I should ask to see a dietitian, and try an elimination diet. Maybe go see an allergist? An internalist? Someone with ear, nose and throat training? A sleep clinic? Or just suck it up and live with it until things improve? Does this ring a bell with anyone? What do you think?