Thanks for your replies, guys!
Terri- In November I just randomly developed tinnitus in my left ear. Sometimes it will randomly get louder for a few seconds, then return to its normal tone. It started up in my right ear, too.
I had a hearing test three months ago at the ENT doctor's, and my hearing is fine, so he wasn't really concerned. He's basically sending me for another MRI because I asked for it. I was worried about an acoustic neuroma (benign tumor that grows on the auditory nerve), but he says as long as there's no hearing loss, dizziness, and it's in both ears, it's most likely not. Sometimes people randomly develop tinnitus for no reason.