I have a lump, in my neck , underneaththe jaw bone that moves around, and has pain in it.what it's it.?

Lymph Gland?: It may be an enlarged lymph gland.Other possibilities are a cyst or an abscess please get it checked by your doctor to find what it is and if it needs any treatment.

Infection ?: From what you describe, the fact that the lump moves and is painful, indicates the problem is probably an infection. Malignant or cancerous lumps most often are fixed and don't move, but your condition is not normal and you need to see a dental or medical professional to establish a diagnosis and course of treatment. Don't delay, as an infection can be deadly!

Lymph node: Likely you have infected lymph node which is tender. See your primary physician.

Lymph node: Likely a lymph node that is enlarged. The other possibility is a salivary gland that is prominent. These are almost always benign at your age and don't require further evaluation unless they persist, or change in some way.