Radical Change in Behaviour

I do not know where to turn. My 15 year old son, who has always been good and caring, seems to have totally changed in the last six months and now yells at me and has recently raised his fist at me and given my husband a black eye. He also seems to have a lot of money and we don’t know where he is getting it from. I am too ashamed to tell my family or friends about what is going on. I need help before this escalates any further?