I, too, developed the strange pulsing tinnitus in my non-AN ear a few months ago. I had my AN removed in December and was doing very well, but about a month ago, started getting more dizzy again along with the pulsing tinnitus in my good ear, as well as back to being tired all the time. I went to my gp who started with blood tests. My thyroid levels came back low and they did some additional tests. It's hypothyroidism, which can be treated with just a pill everyday for the rest of my life. Tricky thing is finding the right dosage. I have been reading up on hypothyroidism, and some of the side effects are exhaustion because the body's metabolism slows down, and tinnitus, which can be pulsing. I'm two weeks into the medication now, and the dizziness is starting to get better again, along with my energy. Haven't noticed a change in the tinnitus yet, but they said it takes many weeks go adjust to the medication, which still might be too low. They will do a blood test every 6 weeks and adjust the dosage if the levels are still too low. I too was scared since I thought I was relapsing because of my AN, but it turned out to be totally unrelated. Will keep you posted on whether it helps the tinnitus.