I have a similar situation. Last new years eve I got seriously ill (vomiting, and diarrhea). I went to a doctor and told her I have lower right side abdomen pain, I felt nausea, vomiting, low grade fever, and also lost some weight. They tested me for all kinds of thing. My ovaries, my gallbladder, appendix, my kidneys, my lungs. You name it i've had all the tests all except my stomach. It's been 11 months since the incident, they still don't know what's wrong with me, but they tell me i'm in good health. I still don't know whats wrong with me. So I have scheduled an appointment with a gi. Hopefully they can tell me what's wrong with me.
To make a long story short. I suggest that you take a more proactive approach. Don't let them tell you-"you're okay"- when you don't feel fine.
Make an appointment with another doctor, get a second opinion.
I wondering if you feel ill (gas, nausea, etc) when you eat. If so, you should make an appointment with a gastroenterologist. (you might need a referral from your doctor)
i hope this helps