Anyone know what's wrong with me?

Well, I've been sick for 3 years, done every test imaginable... But as of right now, when I stand I feel off balance, I can't describe it. My vision is weird, it's almost like an out of body experience. Not in a fun way. And I'm always sick to my stomach. And I get occasional headaches. Sometimes I shake, I go from diarrhea to constipation all the time. And lately I've had pain in my back kidney area, the doctor said it was too low to be my kidneys... Occasionally I've had a fast heart beat/short of breath. Nausea is the biggest factor (I never throw up). And I've tested for everything. I'm 16. I just want to be normal again, I don't even know what that feels like sometimes.