Am I a candidate for Invisalign? I have TMJ and have headaches often (Photo)

There is only a single photo but it does show that you have a small axilla and a narrow mouth.  Coupled with your history of TMJ disorders, headaches and previous orthodontic relapse I suggest you strongly consider correcting the underlying problem of the narrow maxilla.  This is associated wiith a narrow nasopharyngeal airway, forward head posture, snoring, UARS and Sleep Apnea dependiing on age.  Definitely contributes to headaches and jaw issues.There is not a full smile picture but I assume you have dark buccal corridors and possibly dark circles under your eyes.You can address all of these issues with a DNA Appliance, Oral Myofunctional Therapy, oral myology and Mewing but Invisalign addresses noone and may make the TMJ issues worse.

80% of my TMJ patients had orthodontics as a teen.   the orthodontic movement puts teeth in a position that the body doesn’t like.   The muscles fight tooth position.  Invisalign may help or it may not.   the goal would be to move your teeth away from the tongue to give it more space.