My son is almost 11 weeks old. I had him on Enfamil Prosobee because of a sensitive tummy and I've had enough of the constipation it's making him have and he acts in pain all the time. I went to the doctor yesterday and she told me to try Nutramigen... So I did. And he still won't really eat. It's been 4 hours since he ate last and he only ate 2oz and cried and spit it out. Idk what's going on?? :(