What to do because my teeth grinds against my teeth by itself and it's really painful how do i stop this?

You cannot: Teeth grinding or bruxism is a central neurologic phenomenon. The only thing we can do is to manage its effects by nighttime bite devises. One in particular is effective in reducing the elevating muscles force by up to 70 percent called a nti. Others are full arch bite splints called nightguards that protect the teeth from enamel wear and damage.