@Sen It could be caused by several different things. It could be your temporomandibular joint or that your bite is off on one side or both sides. From that some teeth from gum swelling may not be giving you an even bite. This could be caused by grinding. Many times during sleep we don't realize that we are grinding our teeth.
Problems as you mentioned can also be caused by using a mouth guard at night. If a mouth guard is being used, it should be extended enough to cover your back teeth. This is in reference to using a mouth guard for either top or bottom teeth. Just a top or bottom guard is needed, but it must be comfortable, not bulky and cover all your teeth. Otherwise it will cause the problems that you are having.
There's many reasons for jaw problems and maybe a consultation with a dentist, maybe a specialized one would help. I'm having the same problems and my dentist said that I'm having the problems mentioned above. I use a top mouth guard and it doesn't cover all my back teeth, so it causes hyper extension when I open my jaw wide. I need a new mouth guard, as my is hard and doesn't cover my back teeth. My dentist has only hard guards. I feel that I need a medium guard, but that may not be best either. From gum and muscle soreness, bacteria can set in causing a second level problem.
First my dentist wants to clean over my gums and treat with an oral rinse. Most oral rinses wouldn't interfere with tinnitus. Then after my muscles and gums settle down, he will plain some teeth 5 seconds on 10 seconds. Then he will make a thin mouth guard that will cover all my top teeth. Some like a bottom mouth guard.
None of what I mentioned may be your problem, but grinding or placing pressure on my teeth has added to the problems that you have. Dental trauma could be another possibility. Having jaw opened wide for too long during a dental procedure. If the neck is bend and not relaxed straight to shoulders it could cause problems that we have.
A bend neck, and/or pressure placed on jaw during dental can cause tinnitus or increase it with a high pitch somatic tinnitus. This is how I got somatic T. The high pitch and stress causes me to grind making my situation worse.
Note: Sleeping with neck bend and not straight to shoulders can add to these problems.