Yes, I'm often in a college environment and I can attest to the horrible food choices at the cafeterias. You'd be better off skipping the food service if possible, or looking at the menus ahead of time and picking and choosing. That's hard tho, especially on the social life.
Sounds to me like you've done alot of things that have already improved your health. You also cannot expect things to happen overnight. The natural way is not instantaneous like the way a presciption med can tend to work. But you are doing things the best way for yourself long-term.
You still didn't mention what sickness you had - that might still be lingering somewhere in your body.
Blood type O's have the strongest stomach acid and can digest the meat best. However, weirdly for you, grains and dairy should be awful for you. The strong stomach acid might explain the burping, etc.
If you are really serious about continuing to help yourself, and feel like you've hit a roadblock, I can probably set you up to talk to my doctor sometime, if you're interested. He's a busy man but is editing a book right now and has some down time in September. Do you live in the U.S.? Does this sound interesting to you?
One more thing - is it possible that your hormones are involved in all this? Do you bodybuild at all?
Keep on, I'm so impressed someone your age has done all this on their own -