Swollen painful moving to touch lymp node under jaw, on one side, blood test thyroid test echoghraphie are normal. i have neck stiffness and maybe tmj. what could be the cause please?

A painful enlarged lymph node usually indicates an infection. The mouth and that side of the face/neck have to be checked for cause by your MD or by ENT

infected teeth, gums, tongue, tonsils, submandibular node that you are feeling, a duct stone or a common cold to name a few. I we could talk and I could examine you we could narrow this down. Do the same with a Dr who knows you would be even better.

Lymph nodes act as traps for infection, usually bacterial. See you Dentist to evaluate for diseased teeth and/or gums.