Everything i eat upsets my stomach, has anyone else had this problem? What was the solution?

I'm 18 and I've had stomach problems since I was about 11, but NEVER this severe. I had a upper and lower gi when I was 11 to see if I had ulcers, and nothing. They thought I was just allergic to dairy. But now, literally everything I eat makes me sick. Everything makes me poop immediately after I eat, and I get the WORST upper abdominal cramps & bloating. It hurt so bad last week for two days I was curled up in a ball & it was like I had no control over my stomach muscles...my stomach had caved in & i looked like a skeleton. It usually goes away after a few hours or when I go to sleep but I woke up feeling the same. I went to the dr two weeks ago & was tested for hp lori, an infection that attacks the intestines. It was negative but he put me on antiobiotcs just in case, I go back tomorrow and the meds didnt help at all! Ive heard anything from IBS, to something wrong with my gall bladder, to celiacs disease. Has anyone had a similar problem? It will take months to see a GI dr and I cant suffer any longer :(