I hope this info is of some use to you. This is advice I give to my patients when this seems to be a one off event, or we arent sure how bad the problem is going to be.

TMJ dysfunction, or myofacial pain sounds like what you are having. They often are used synonymously, but I find myofacial pain is more common, nothing too exotic myofacial pain means muscle face pain . Usually it afflicts people under stress, or with some jaw alignment issues. I often encounter it with patients who work on computer with poor posture ( Im catching myself hunching as i type this).

Ask your partner if he hears a grinding noise at night, or alternatively see if you catch yourself clenching hard during the day or when concentrating.

It often causes a cramp in the muscles of your face near either your temple/ lower jaw.

Trismus ( inability to open your mouth ) is a common problem when the muscles spasm.

Because a dental splint isnt a cheap investment, especially if this is a one off, I often recommend getting a cheap "boil and bite" mouthguard from the chemist and wearing this at night. Get a small childs one, and even trim it with some scissors so its not too bulky. If this works for you , and you dont mind wearing it at night, perhaps seeing your favourite dentist for a custom made splint. Its an investment, but a splint will last longer, and you know that you will actually wear it after spending the cash on it.

Also, considering that posture and stress can trigger this, a good massage of the neck with your physio/ masseuse can give relief and perhaps reduce a recurrence of symptoms.

Opening the bite tends to reduce the pain from the muscles and give some relief. Also it tends to cut the grinding reflex. We dont fully understand TMJ dysfunction, its actually considered a bit of a black art in the dental profession. Plenty of opinions out there. But i find this tends to give a conservative and inexpensive approach to most common encounters with it.

Hope that helps.