serious formula issues

Ariel

my first two boys had to be on nutramigen. I had my third 5/20 and by day two in the hospital they put him on nutramigen. fast forward to almost two weeks old he had zero gas but diarrhea every 30 minutes for over a week-it was terrible he lost over a pound. we got switched to alimentum.

the gas and fussiness came back and the switch made him constipated. the Dr had me mix karo syrup in every bottle. finally after five days constipated he now has bowel movements, but the fussiness and screaming every hour are back.

we've tried everything even gas drops-I know all the colic tricks as my other two had serious tummy issues but not this bad.

My son just hit three weeks and we may have to take him to a specialist but I'm curious if anyone else had issues like this and what I could be looking at.

I'm pumping and freezing since the Dr said not to give him the breast milk until we figure out what's wrong (it made him and my other boys worse-so I'm going to use it when I make baby food if he can handle it by then) but I'm so stressed I can't keep my supply up, so any help regarding the formula issues would be great.