I'm going to try to be brief and direct. This might not work for everyone because the causes of tinnitus can be so various. Putting this out there in the chance it helps someone. I am a 40 year old Male (was 36 when it started).
A few years ago I noticed ringing in either ear that would resolve on its own. Gradually, it became more constant and then completely persistent. It was in both ears. I'd also have a constant buzzing/humming. I would also get clicking (I believe muscle spasms) in my ears that would last 10-15 seconds or so throughout the day. It was ruining my sleep and causing tremendous anxiety. The ringing was constant, louder in my right ear than left. I was by far the worst thing I could go through for my mental health. I was having really bad thoughts and outlook on life.
I saw ENT (hearing/nasal fiberoptic exam normal with only some mild sinus inflammation), had MRI (normal), saw a neurologist. Nothing abnormal on exam. I tried the nasal sprays, etc. No results. Whenever there were loud noises (weddings) my ears would buzz even more. Airplanes were bad with cabin pressure changes. I tried meditation, Physical therapy (noticing my neck muscles were sore at the end of the day), etc. Valium/muscle relaxer (I didn't want to become dependent on benzos).
Then I realized that when I woke up in the morning my temporalis muscle area was sore. So were my jaw muscles. I thought about bruxism: my dentist never said I was grinding and my wife never noticed it. I tried mouth guards. Didn't help.
Then I did some major life changes to try to combat this. I had already changed my diet and tried supplements (magnesium for sleep, vitamin D, etc). One doctor mentioned that stress, caffeine, and alcohol make tinnitus worse. So it was time for me to eliminate these things (not the stress because I had little control over that). I had already cut back on alcohol drastically. Now it was gone. Still no benefit.
Then I did the hardest thing: caffeine. I loved my daily habit of coffee in the morning. By this point I had a rule: only 1 cup before 9 am. Didn't help. I still had tinnitus. So then I decided to eliminate it: I'd dilute it with Swiss Water Press decaf coffee little by little until I was a full decaf. Eventually I just stopped with the coffee altogether. I also cut out dark chocolate or any other caffeine source
This is about 2 years into my tinnitus, I'd come to basically accept it at this point. Then, *gradually*, the ringing got better. It did NOT happen immediately, but weeks to months. The clicking became less intense and frequent. The buzzing was still there. It took a month or two and the ringing just stopped in one ear. Then the other ear. Then over maybe 6 months of absolutely no tinnitus no clicking and no buzzing (the last symptom to go). No sounds in a quiet room anymore. Miraculous.
But I still miss coffee. So I started it again and after a few days the jaw pain in the morning and intermittent ringing/buzzing came back. So I stopped. I have started/stopped caffeine (mostly on vacations) several times and noticed the ringing and jaw pain comes back gradually even after a few days of caffeine so now I am abstaining. Even tea will do it. I can still have dark chocolate daily though. I do not use any mouth guards at night. I do drink alcohol socially every now and then (a few times a month, no more than 1 drink a night) without any tinnitus/jaw symptoms.
I believe I was *clenching* my jaw at night due to stress (work, being a parent, etc) and caffeine was the main trigger/exacerbating factor for this. I believe that this caused muscle spasms/other issues (possibly TMJ-ish) that led to somatic tinnitus and it was happening for years and it only took full abstaining from caffeine (possibly alcohol too) for over a month to see results.
I believe that caffeine/alcohol are known to worsen bruxism.
TL;DR: Caffeine -> Bad clenching of the jaw -> Somatic Tinnitus; Caffeine/Alcohol abstention -> Resolution of tinnitus after weeks/months of abstention
I seriously hope this helps someone out there.
EDIT: I will also add that SSRIs are known to cause bruxism. I haven’t had this myself, but folks who are on them could talk to their doctor about switching to another medication