Hello~I don't think it is anything to worry about, especially since your doctor has checked you and said all is well. I am glad, however, that you are letting her know again, it is always best to be safe than sorry. I have had something similar, but it didn't last long, I think mine was due to stress.
I will hear that as well from time to time. This could be pulsatile tinnitus. How is your blood pressure? You've been evaluated for coronary artery disease? You are very young, so would not really think this is going on. But bring it up to your doctor. Just to get checked. The ceratoid artery is in that area. If your cholesterol is high enough, that can cause pulsatile tinnitus. Normally, my doctor has said not to worry about it. But your doctor should be aware that this is happening to you. High BP is one reason this will happen. Hypertension is familial. https://www.health.harvard.edu/diseases-and-conditions/is-it-worrisome-to-hear-a-pulse-in-my-ear