I know "all" about TMD. I got it from the disabling accident 28 years ago when my jaw was knocked off both hinges...

the night guard will help keep you from grinding your teeth down...so wear it... even if it's just a sport's mouthpiece (though one you can heat and conform to your teeth is better).

Psychotherapy can help also, allowing you to handle anxiety better so your grinding (bruxism) is minimal..and the tightness in neck etc reduces or relieves.

Yes, physical therapy helps reduce the knots in your muscles, which should minimize the jaw spasms. You need to treat it..it doesn't get better on it's own, and worsening you will need jaw surgery in the future... treat it... find a doctor or clinic with sliding scale etc. but treat it!