It's already been said, but it sounds like acid reflux. The same thing happened w/ my daughter. Once, we put her on a prescription medicine (we use Axid), it helped a LOT. We actually started her on it when she was a WEEK old (kind of scary) but it worked! My pedi said it's very common in babies. My daughter was always fussy during and after feedings so I asked her Dr about it. When feeding, does he arch his back a lot, and kind of try to throw his arms/legs back? I BARELY mentioned that to my Dr, and before I could even finish, he said "it's reflux" (apparently they do this b/c they are trying to elongate their esophagus b/c it's burning). W/ reflux, they do tend to be gassier because they swallow a lot, trying to keep spit/milk down (or at least, my daughter does). I was concerned at first b/c she never "spit up" and i figured w/ reflux i'd be seeing stuff come out of her mouth, but the dr said some babies don't spit it out, it just irritates the esophagus. I also use Mylecon, but the Walmart version (MUCH less expensive) after every feeding, and try to feed him in as much of an inclined position as possible. According to my Dr, you can't overdose them on Mylecon, and it really seems to help.