I've become a very mean person. i'm angry almost all the time. either angry at others or self loathing. i feel like something is wrong mentally.

See a professional: If you are in otherwise good health and no endocrine problems, then I would suggest seeing a psychologist to help you figure out what is causing the change in your moods. Psychologists are impartial, are there to help you understand and to deal with your own feelings. They do not prescribe medications. Perhaps your anger is misdirected or disguising another issue