Juliet. Just don't worry. Forget the damn fan and just live with the rhythm. In a while it will become a friend you'd miss if it went away.
I was distraught when I was diagnosed with tinnitus at age c 35. Well, when they told me there was no treatment. After a while it was insignificant.
It's probable that tinnitus is generated in the brain. The ear gets damaged, and the brain turns up the volume to compensate for the sensory hairs that are failing to produce sound. It makes a lot of sense to an electronics engineer, but no help to the sufferer.
Hey, I'll tell you what. Tinnitus is not as bad as daftness. I started reading this thread, and in a moment constructed an answer in me brain about my wife. It wasn't until I reached a post by one, Loose rivets, that I realized I'd already written it. So long ago, and the memory of poking that thing into the Rivetess' ear was like it was yesterday. Oh, my.
The comment about the GP was very real. He was a troubled soul who would, on principal, refuse to believe anything any member of my family said. The point being, seeing that 'spray' of blood vessels was very, very difficult to do, and I wouldn't be surprised if several GPs failed to get the darn things in focus.
So, my post is clearly divided into three parts. One is tinnitus that is neurological, the next is a very definite vascular structure that is almost certainly causal. The third part means that all you have to do is make sure there's not a problem that needs skilled intervention right away. Get a referral to a specialist, but be 99.999999% sure nothing is going to be found.