Is my baby being over medicated?

My little boy is only 5 weeks old… he had some issues with crying alot and spitting up ALOT… i mean even when he hasnt just ate… He started out on similac advanced.. then was switched to Enfamil A.R. for his refluxing.. it helped with the reflux, but it made his poop to hard and he cried and cried and was very gassy… so then we were told he had a milk/soy protein allergy and reflux.. and we were switched to Nutrtamigen formula and zantac 3 times a day… Well the throwin up got worse (im guessing because the nutramigen is so thin) but the crying and sleeping got better…. So the doc now wants to add Prevacid 30 mg solutab once a day along with the zantac .7ml 3 times a day… ok.. If the prevacid is not going to help the throwing up then i feel he does not need to be on it, i dont want him on all this garbage if its not going to do anything… Please share your opinions… and i feel that 30mg is alot for a 5 week old.. plus the zantac , i mean that seems like it would upset his belly more..