Hi Michelle,
Ivy was exactly the same. It was only after months of vomiting that a paed (bless his cotton socks) suggested allergy to cows milk protein. We tried soy for a month and it was no better. He changed us onto pepti junior, which is a milk protein free formula, and in a few days she was like a new woman. She still had bad vomity days, don't get me wrong, but she was alot better. Perhaps something you could look into?