Temper, the ugly side of me

What gives people the kind of temper that ends up making scenes in the local blockbuster? I am learning that it has to do with illness... I have a history of hypothyroidism. My body is unbalanced, everything goes slower than its supposed to, including my metabolism (that really makes me upset). I eat right and exercise, yet there seems to be no hope for me. But that's not what I want to talk about. I am beginning to get upset over the simplest things, like not being able to rent a movie at blockbuster because my mom forgot to put my name on her account. I could have let it go no problem. I used to let stuff like that slide all the time, but lately my syptoms have been getting worse. Eva, the girl that rarely talked in HS... Mostly because she just loved to observe everything and everyone around. The fact is, I haven't always had moments of rage. I never understood how someone could make a public scene... It just seemed so pointless and horrible. I am beginning to realize its not always that they want to hurt anyone's feelings, it may be because of a chemical imbalance. I know for me it is. I really didn't feel good about myself after I made a scene in public. I felt terrible for the people around me and completely embarrassed for myself.