I m feeling like my upper teeth r changing position like m having over bite never had any prob bfore.never had ny braces or anything.wht cn b d reson?

See a dentist: teeth shifting can be a sign of periodontal disease, best thing to do is see a dentist and find out what the problem is

A few thoughts...: We all change a bit as we age, so that can be part of the issue. Tongue thrusting, periodontal disease, and a bite that is off can all also contribute. Your concern is valid, but you'll need to see a local dentist for a proper diagnosis and care. All the best..