I spent my life up until just a few weeks ago undiagnosed; however, my parents knew something was different when I was a kid. They took my to so many doctors, psychologists, psychiatrists, you name it. They mainly took me because of my uncontrollable meltdowns which I had very frequently. One doctor told them I had food sensitivities/allergies to mostly everything and they were supposed to remove everything from my diet with dyes, preservatives, chemicals, caffeine, etc. All I was supposed to eat was meats, fruits and veggies, and very plain grains (by that I mean, the only cereal I was allowed to have was unflavoured wheat puffs---I was two or three and I still remember them. Yuck!) Anyway, I stopped eating everything but water so my parents stopped it, though I really wish they hadn't.
I am also allergic to many drugs, but that is due to Malignant Hyperthermia--I cannot have most anesthetics. I have some sensitivities to some pills, and I cannot no matter how hard I try, stomach liquid medicine.