Hi, Our Baby Is Now Six Weeks Old And Has

Hi, our baby is now six weeks old and has been drinking Nan AR all the time. He still vomits after feeds sometimes only a little and sometimes a lot. He doesn't settle after feeds, I don't think he has colic but definitely cramps. It seems just overall if the Nan is not good for him. Will soy be a good alternative or must we just try another formula like Novolac?