Morning, I just posted something kinda the same as your post.
Do you have any fullness, or popping or crackling in the ears? I have chronic sinusitis, and I go through horrible bouts with fluid and pulsatile tinnitus. I get it to the point where it sounds like a herd of buffalo running in my head.
You mentioned the ER, have you gone to an ear nose and throat specialist? My suggestion is start there. There are many tests they can do to help you figure out why you have this. I have heard that you can have a heightened awareness to it, once you know it's there. Sometimes you can hear it at night when you are laying down because it is a lot more quiet. You don't have the everyday noises drowning it out.
Try not to diagnose yourself, and don't google it. Make an appointment with an ear nose and throat specialist!