Hi, tender area under jaw towards where wisdom tooth is. may be under it. wisdom is partly emerged, never had issues. no pain in mouth or on biting.

Don't know your age.: I recommend dental examination and the wisdom tooth may well be the issue.

Looks like: Looks like the inevitable caught up with you. Partially erupted (partially impacted) wisdom teeth act as a pump to wick bacteria into the jaw bone. You probably have an infection. Before it spreads and worsens, see an Oral Surgeon.

Wisdom tooth: Might be the problem. See a local oral surgeon for an evaluation.