Mom is crazy. As some form of therapy she pressed my back w/ her finger joints and beat it with her fists. Worried about physical damage done to body.

See your doctor. See your pcp without delay for physical exam for possible injuries from this rather bizarre episode. What do you mean 'therapy'? No excuse for physical aggression. Does your mother drink, is she mentally ill? Ask your pcp for the name of a mental health professional to see for coping strategies. Hope this helps you.