Tinnitus cause? Is there some infection?

I have tinnitus since 2-3 years. Had a brain mri, neck usg all fine. Nothing was shown, i am right now habituated to it. Audiometry tests showed normal with slight hearing loss in left side audiologist said its fine. Impedance + pta both were done. Initially tinnitus started in left but i have it in both sides. Now my problem is sometimes, it happens like i am sleeping on 1 side of face or maybe sitting also, there will be huge spike like the older tv beep and will last for few secs 2-3 seconds maybe and gradually go down, i found out when i modulate my jaw that time it comes down more sooner, and while this happens, the background sounds will get dull, say if i am hearing a fan sound, it will get diminished. I believe further investigation is required but the local ent all they do is prescribe more and more medicines. Also after this spike occurs, i see there's a slight itching inside ear and a pungent/weird smell in throat when i force our post nasal drip. Is there some infection?