What can you do or take for relief of tinnitus/ringing in the ear?

Probably not what you want to hear but you need to take your butt to an ENT to make sure it is not one of the dozen causes associated with something more serious. This could be a warning sign. If benign then they can do either a maneuver or prescription that might help. Good luck and I don’t just play a doctor on tv…lol

See a doctor, get it confirmed and in your medical records. Ensure it is recorded with the VA. Get a referral to a specialist. Good luck.

Can't tell if you're AD, Reserve or Veteran. If the latter, the VA will provide you with hearing aides and I've found that they limit the tinnitus. Tinnitus will also get you a 10% Disability Rating which, by itself does not actually get disability payments.
Beyond that, like when trying to sleep, there are electronic devices readily available that make "white noise." Verious settings will help mask tinnitus. I'm lucky in that regard - my tinnitus for YEARS was the same frequency as cricketts and as an avid camper, it was easy to literally be lulled to sleep. More recently, along with that is a "roaring" sound but somehow I'm not overly bothered by that either.