Advise on a workplace issue. possible HIPPA violation?

I had been feeling very tired and almost depressed for a few years and had blood work done to see if it was something with my health. I found that I had very low testosterone levels. I was referred to an endocrinologist and an hrt. Under the supervision of my hrt therapist I now inject synthetic testosterone to keep my levels normal. I am a firefighter and my Captain and I had a conversation on this subject after seeing a commercial on tv. I confided in him and explained my condition with him and told him how much better I feel since I began therapy. It was a big mistake on my part because now it has turned into a gossip mill at the station when I leave the room. Several of my co-workers have brought it to my attention that he talks about it all the time and says he doesn't think a 40 yr old man needs to be injecting testosterone. I am getting sick of hearing this from my co-workers and at first I thought it would pass and he would find something else to talk about. Unfortunately its been going on for a couple months now and I am about to confront him and ask him to stop before a bunch of rumors start about it. Although I feel it may be to late for that. Rumors seem to get out of control here and I don't want to be called into the Chiefs office and be accused of using steroids or have my medical condition a topic of discussion at the firehouse for every shift at every station. Like I said I have a valid doctors prescription and am under close supervision with my testoterone replacement therapist and my hormone replacement therapist as well as my family doctor. I get my bloodwork done regularly to make sure everything is ok and feel better than I have in years. This situation is frustrating and is stressing me out. What should I do?