Similar thing happened to me about 8 years ago....diarrhea instead of vomiting every time I ate. I lived on PowerAde and saltines for about 5 months, lost 40 lbs. Had the million $$$ GI work-up, to no avail. I am convinced it was my gallbladder, although all GB tests were negative, as was endoscopy, colonoscopy, CT scan, abdominal ultrasound, tests for GI bugs, parasites etc. To this day, no one can give me a good answer about what it was, and I loved my doctors and they truly did everything they could and my medical doctor is a fantastic diagnostician and I even had him stumped.
About the only other thing I could possibly have attributed it to was Celebrex, which I had been taking for foot problems for about 6 months prior to this issue starting. I stopped the Celebrex because the foot issue cleared up and slowly the GI thing started to clear up as well. I will say though that my stomach is still more "delicate" than it used to be.
If you have not had an endoscopy, colonsocopy, ultrasounds etc., then your doc is missing the mark. And losing 35lbs. from vomiting is nothing for him to be happy about...it's the wrong way to lose weight.
GI things with women can be som difficult because there's the GI possiobility, the Ob/Gyn possibility...there's a lot of "stuff" in our abdominal cavity!