Biting down on my teeth

Every few seconds I bite down on my teeth, over the past few days it’s gotten worse and I’ve been doing it more. I can’t stop, I try but I can’t. I do it without even realizing it. I told someone about it today and as soon as I got done talking about it, I bit down again. It’s like a habit. My teeth are starting to hurt from doing it so much but I don’t know how to stop! Any ideas?