I would get a second opinion. Or they could believe it to be a simple functioning cyst that isnt a large size. Most dr's play the wait and see game if its less than 5cm. And will likely talk about putting you on birth control to help disolve it if you arent on it, and should do a follow up scan 2-3 cycles later I have found.
For me, I have simple functioning cysts that form in my left ovary (these are usally related to ovulating), regular 21 day use of the pill was not working, so now i am on the pill for 3 consective months, then i have a period, and that has made the cysts stay away so far up til recently as I had to stop birth control after my surgery to remove another cyst and R ovary in Feb.
I would absolutely get another opinion. My family dr wasnt leaving it alone when i told her how much discomfort i was in (and when she experienced it herslef during my yearly physical)... Make sure you're seen by a OB/GYN because they usally know a little more and how to help you with the cysts.
They said it will go away by its self. So i just have to deal with it
They didn't tell me how big it was and they said they is nothing they can do for me.
Perhaps you should see a doctor about getting it removed girl!
Take care
K