Appendicitis. Had it when I was in first grade. I started to feel pains one night, my parents thought I was just getting a stomach cramp. So the next day they took me to the doctor, one guy sent me to get a CAT scan. Apparently my appendix had burst while I was in the waiting room for that. The doctor said I'd be fine for the time being, but that night the pains of it hit me like I'd been shot. I started screaming, and my mom took me to the emergency room of a children's hospital in Memphis. We had to wait about half an hour, and then they ran another CAT scan on me. The only thing keeping me alive was a pocket of fat containing the stuff from it, and they gave me surgery the day after. Was stuck in the hospital for a week on a fluid diet (jello, chicken broth, ect.). I remember spending hours each night screaming from the pain ;-;
Other than that, I've had strep throat several times.