Hey pudd! I saw this post and just had to reply on it. A good friend of mine had the EXACT same symthoms as you describe.. It turned out to be smal "tunnels" in the brain, I dont know the exact name of it it, and I know it sounds alot worse then it actually is. They did one operation on him where they sealed those "tunnels" and now he is back to normal.
I might be wrong, but that sounds just about what he had. He now lives a life without any tinnitus or pulsive sounds..
If I where you I would check up with the doctors and maby question them about this, they might have some answers/ideas about it.