Hi, two years ago i suffered from sever depression. i cried for days on end, self harmed, contempated suicided and even attempted it. I never went to the doctor as i was too embrassed about it, but i spoke to a close friend who helped talk me out of suicide. After this attempt i felt so ashamed of myself that i saw i would never self harm again. I was happy and 'normal' for two years after that, but recently I have been over whelmed with a huge sense of sadness for no reason. Some days i can be extremly happy and others extremly upset and crying for no reason. I recently fell back into self harm as it made me feel better, but i have stopped again as i know it is stupid and wrong. What could be causing this extreme highs and lows? Could I have some form of depression or is there any biological explanation?