I pull the skin off my feet compulsively

I do this alot. I sometimes do it without even realizing i do. I sit there and pull of my skin while im on the computer and sometimes i even take the nail clipper and cut it off. I dont only do it on my feet. I do the tips of my fingers, sometimes my friends even ask me what happened but i just say i got burned because they are so red, and i do the inside of my cheeks. My mouth always tastes like blood and im afraid peopke can smell it, but i just cant stop. my fingers always hurt if i touch something the least bit hot, and they are in so much pain if i touch something like a soda. I cant even open s bottle on my own without being in pain, ajd my mouth byrns if i were to eat salt or lemon. I need to stop but i dont know how.