Most likely they'll try to tell you it's colic but if you feel something is wrong keep pushing it.

My oldest was a projectile vomiter for the first 8 months of her life. Not really gassy but would throw up and completely miss herself and it go halfway across the room. Turns out the flap that leads from her esophagus to her stomach (which normally closes when nothing is being eaten/drinking) wasn't fully mature so it was just a waiting game. But scary at times, had to keep an ear out if she threw up when sleeping @_@

I wish you luck and hope he gets better soon!