Try to check heavy metal toxicity...some of the people here with AF/Hypothyroidism got it from heavy metal. Not all though, it's better to check, esp. since you have TMJ. Also do you have any Amalgam fillings (or once had but taken out already)? Or whether you have root canal &/ cavitation issue?
Heavy metal toxic can be from any source (air, water, food, etc.) But the tooth related source is one of most common (and easy to check) but often overlooked.