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Welcome to NeuroTalk.
Wow, what a unique condition you have. I can imagine how annoying it is. I have constant tinnitus. Had it for decades. My ringing is at about 1100 hz. It's very loud right now but it is sometimes not so loud. Drinking a bit of water can make it very loud. I have had to learn to ignore it.
Your thought of muscle twitching sounds right. I found a good web site by an ENT. It sounds like you need to find a better ENT. Maybe a hearing clinic can direct you to a good one. Here is what I found:
Irregular Ear Clicking or Vibration Noise
Have you tried adding magnesium to your diet as a supplement ? The web site suggest mag oxide but mag citrate or other non-oxide form of magnesium is better absorbed. Anti-seizure meds can also help in some.
The Vitamins sticky at the top may be of help. Nerve/brain nutrition may be useful.
You likely need to find someone who can determine it this is palatal myoclonus or middle ear myoclonus.
It sounds like a hick-up but in the palate or middle ear rather than diaphragm.
My best to you.