Typical day before this started:
Wake 7:30 am
Nap 9:00-11:00
Nap 1:00-2:30
Nap 4:00-5:00
Bedtime 7:30 pm
It's difficult to specify eating times because he nurses basically whenever he wants. Long nursing sessions are after waking, after each nap, and before bed, but shorter ones happen at other times as well. He is only bottle fed by babysitters, if my wife is out of the house at bedtime, or if there's otherwise a reason she can't nurse (she still pumps once before we go to bed, to maintain supply & to make sure we have some in bottles for babysitters, etc., and if the baby happens to wake up immediately after she pumps, I'll give him a bottle.) So yes, our schedule isn't as rigid as most suggested on this forum, but the sleep has been pretty consistent.
We tried doing a PU/PD routine tonight. He's asleep now, after an hour, but not really in the way we planned. We did his nighttime routine (change, pajamas, nurse, read a couple of books), but he started fussing during the nursing (and in retrospect probably didn't get quite as much food as he needed) when he realized he was going to be put to bed.
Unfortunately, PU/PD went about as I'd worried it would -- he started crying the moment he touched the crib, and did not stop for the full hour I was at it. Patting, shushing, picking him up, etc. do not comfort him at all. He did kind of fall into an exhausted sleep when picked up twice -- and both times was out less than 60 seconds before suddenly startling wide awake (eyes open, fighting, arching his back, etc.) and much more upset than before. After an hour, I was concerned that he was still hungry since his nursing had been a bit abbreviated before (and from the effort of crying for an hour), so had my wife come in to nurse him. He ate voraciously for 10 minutes and then fell asleep instantly on the breast. So, so much for putting him in the crib awake -- she put him down, he didn't wake at all, I stayed with him with a hand on him for 10 minutes (expecting the 5-10 minute wakeup of the last week), but he was out like a light and still is (it's been about an hour.)
It remains to be seen if he'll be up every 2-3 hours again tonight.
Thoughts:
1.) We have to make sure he fully eats his before-bed meal even if he's resisting that. I think it was a mistake to let him stop nursing before he'd had enough; we may be better off interrupting the night routine and letting him be awake longer to make sure he really has his fill. A hungry baby isn't going to sleep.
2.) We could probably get past the 5-10-minute wakeups just by staying with him with a hand on him for 10 minutes after he goes to sleep. This would be the path of least resistance for sure, but...
3.) I doubt it would do anything about the night wakings, which are also an issue.
As for teeth & developmental chaos, there's no doubt: he's teething (two lower teeth coming in, though neither has emerged), and he's going through tremendous changes right now. He's begun to eat solid food, and is very close to both crawling & sitting on his own, though he can't quite pull off either yet. In the last two weeks, he's shown signs of recognizing that the kitty is a real thing (i.e. not just a stuffed animal, but something that reacts to him) and realized that his parents can get further away from him (crying when one of us walks away, calming down when we walk back), so he's definitely got some development going on right now. It's possible this is just a phase that will pass; we just don't want to end up back in the 10:00-bedtime/up-all-night phase of his first two months again. At the same time, this is probably the first time he's cried for an hour straight in his life, and we don't want to put him through that unnecessarily even with me right there with him.
