Have you tried one of the OTC Monistat kits for yeast infections? Being on antibiotics can often lead to a yeast infection. If that clears it up, then that is what it was. I did have a gyno tell me one time that the 7 day treatment is more effective than the shorter ones, unfortunately.

I am about your age and went to the gyno myself for the first time in years for vaginal irritation, not itching, and because I had developed a cyst after a very long charity ride that I wanted to get checked out. There was nothing wrong, but he prescribed a hormone cream to use, which I haven't gotten filled yet. He says that "all women need it eventually as they age", but my discomfort really isn't that severe and can be relieved after rides with some Vagicaine - now, anyway.

If Monistat doesn't work, then you should go see the doc. You don't want to continue to be uncomfortable.