I'm sorry that it took me so long to respond to your questions but all 4 of us have been sick the last 2 weeks
Anyways to answer your questions. I believe that it is a formula problem because the drs have examined him and physically he is fine. He is intolerant to lactose, soy, oats and wheat so far so cow's milk protein might be an intolerance too! I tried for over a week to get him to take a HA formula and he barely took more than 1 oz at each bottle no matter how hungry he was.
He eats prunes, pears, apricots, peaches, green beans, sweet potatoes, etc. We have tried prune juice but he won't drink it, he likes apple juice but he spits up everytime after drinking it. He'll drink pear juice but it hasn't helped. We cut out all grains about 3 days ago so I'm waiting to see if that has an affect. He was eating barley cereal (1 serving daily), cheerios(1 tablespoon daily) and rice crackers (1/2 daily). It didn't seem like a lot to me but since he is so sensitive to the above things than I'm hoping that is what is causing his problem.
I stopped giving him yogurt when we started on lactose free milk although I'd heard that it can sometimes help. He can't have lactulose because it has lactose in it and our dr hasn't recommended any other medicines to soften things out.