Is it normal to have sporadic mood changes, anxiety etc.

I do that too, just last week I was in the worst of moods. I was crying for no apparent reason, feeling worthless like I didn't have a future and I smoked some cigarettes, I don't even smoke. I took some anti histamine tablets so that they would make me drowsy so I could just sleep the night and day away hoping that when I did wake up all the feelings would fall way but it didn't. Sometimes I worry my confliction with bulimia will kill me so when my heart beats really fast I suddenly start to worry about dying and I obsess over it and cry because I will genuinely believe I am going to die and these emotions are irrational deep down I know it. Today I managed to get out of the bad space I was in for the past week. What changed between today and last week that caused me to feel well again? nothing so I just don't understand why I get these week long anxiety attacks. Don't you ever wish you could escape your own mind? I do. If you need someone to talk to by all means private message, I could use someone to talk to. cheers