My prayers are with you.
Did they consider he just might have a problem with your breast milk. Granted this was quite a while back but I had a friend whose baby kept throwing up breast milk. They tried the baby on a couple of different formulas before they found one that the kid tolerated. Then the baby gained weight fine.
Another reason for throwing up is a hernia. I just saw some show on TV where this 3 year old kept throwing up. They found an extreme case with him where there was a tear in the diaphragm and his stomach and part of his small intestines had slipped up into his chest cavity. The only reason the boy was diagnosed is his mother insisted on an x-ray. Anyway they said that this type of hernia is a birth defect and were surprise it hadn't been detected before. That usually it is just a small amount of the stomach that slips through the whole but that throwing up is a common symptom. Also that it is very repairable with surgery.
As I said my prayers are with you. I also know that it is very frustrating not to know what is going on with your baby. Don't let the doctors put you off - push to get the answers.
