Whats wrong with my dad?

Hes never happy. Infact, hes ALWAYS mad. Even if me or anyone else didnt do a thing. He will always be mad at something. And he always takes things out on me. Never my brother or mom. Well sometimes my mom but mostly me. Right now, just cause i couldnt find my pair of earrings, he literally MESSED up my whole room. Thanks to him everythings all messed up & i cant find a thing. Does anyone know whats wrong with him?? I know he has anger issues.. I asked my mom what was wrong with him and she just said that he has nothing to do since he doesnt work. Im serious, i wanna know what is wrong with his brain.. And the thing is, ive been dealing with this for so long and nobody can help.. /: