For some reason, when I was 12 yo, I took caffeine with great results, even without nutrition. A stimulant and anti-depressant effect. But a couple years ago, I tried it again when I started Peating, and it makes me feel moody and tired at low doses, with plugged ears after I didn't take it for a while. At higher doses, I felt suicidal, I normally never feel suicidal. So is there a way to medically verify an allergy, or do it some other way? I wonder if I can cure it, why would I respond differently now than before?