Even a small hearing loss can cause high-pitched ringing, so it's certainly worth checking that.
I have 24/7 unmaskable tinnitus along with occasional episodes of sound distortion like you described. I hear: songs, hymns, opera, piano music, whooshing, beeping, humming, roaring, rumbling, static, and goodness-knows-else. Sometimes it moves into my brain so I hear things like the National Anthem emanating from the middle of my head.
I am deaf, and it is simply hyperactive neurons trying to 'latch' onto non-existent sounds. My cochlear implant helps: if all I could hear was tinnitus, I'd go insane!
Perhaps try some white noise apps when it's bothersome? I use the Sound Oasis 650 sound therapy machine which also helps. Then there's tinnitus counselling (although my audiologist just shoved a leaflet about hyperacusis at me and told me to live with it!).
I'm on Sertraline and Diazepam (as needed for the worst episodes) because of it. I sometimes take PharmaGaba, but supplements like this are a personal choice and I'm wary of recommending them.
Like you, I have found that stress is one modulator. Seems we have to become zen masters to calm down the noise!