Sometimes my teeth feel loose and shaky and sometimes they are hard as a rock...what might be the problem?

Mobile Teeth: Your teeth are attached to your bone by a periodontal ligament This ligaments has a little "give" to it, acting like a shock absorber. Your teeth actually move about .25 mm to .50 mm which is really imperceivable. Any more movement than that can indicate unhealthy conditions. Please see a local dentist for an examination.

Mobil teeth: You should not be able to feel the microscopic shock absorber mobility provided by the ligament that holds teeth into bone. Do not ignore. Recommend that you see a bone/gum specialist, a Periodontist, to nip this problem in the bud.