Hi Saxman. I too have the same thing but mine is no doubt from listening to live music rather than playing it.
Unfortunately I haven't found any solutions yet and I've had it for about 8 months. The doctors here in Australia tell me to live with it. I'm sure you can appreciate how hard that is. Mine has become so loud that I have to block the artery in my neck to hear people talk. Often I do it for ten seconds just to have peace
Sorry I am no help but I just thought I would give you some support because I know how awful it is. Hopefully the ENT will have send you for an MRI or CT scan to check for causes. If not, get another opinion because sometimes it can be cured.