In recent months, I've been having mood swings that I think are abnormal. One moment I'm happy and optimistic, but then I suddenly feel very low, pessimistic and kind of depressed, and sometimes it's accompanied by suicidal thoughts. Sometimes, I also feel an intense anger throughout my body, where I tense my muscles and have a sharp butterfly-ish feeling in my chest. This anger is caused by even the slightest provocation and it's making me very irritable. I don't why this is happening. I almost feel like I'm on my way to some sort of semi-depression. I no longer care about things that used to interest me, I having trouble sleeping, I'm not doing my homework and assignments on time, and I'm generally extremely tired of school. I'm not coming to the parties, I'm not socializing with anyone, I don't have a single close friend to talk to... My life feels so empty right now. I'm turning 18 soon, so a lot of things are going to change, and I'm both nervous and kind of stressed out over it. There are some bright moments and for the most part I'm not sad, but I'm becoming careless and irritable, and I don't know why.