I hope this clears for you.....
I'm 4.5 months post op and the spasms have settled down but when they are more active they sucked!!!!
The ones I get now aren't as bad.
Are you taking muscle relaxant medication?
I can only relate to you through my own experience so.....for what it is worth:
My muscles couldn't "relapse" because they were not moved - the jaw extension was done after where they attached to the jaw bone.....
BUT, how I use the muscles did have to change as I had physically changed. So they way I chewed, talked and just about did anything with my jaw menath different muscle movements for the muscles.
Beating muscle memory is tough, takes time and can be painful.
I found this exercise that seemed to help.
You keep your tongue on the roof of your mouth. Open your mouth as wide as you can keeping your tongue on the roof. As you open wider, eventually only the tip of the tongue can make contact with the roof.... Now do that for several minutes a few times a day - daily.....
Edited to add: Then you close, then you open, then you close.....you get the idea..eh?
Apparently it helps train the jaw muscles about what they are supposed to do now - build muscle memory with all the parts in their new position.
I hated those spasms.....