Please don't be embarrassed- its nothing to be embarrassed about! I used to work at a Dr office - believe me they heard it all! And much much worse than your rash! People have all kinds of problems Dr are not impressed or oncerned by any of them! You probably need to see your gynecologist bc of the location of your problem. Don't suffer any longer with this Call your Dr honey.
Probably a bacteria infection.Drink lemon water .You should probably stop the birth control for now and see a doc asap! Don't be embarrassed as its their job to care for you.They've seen worse so no worries dear.
You may have a yeast infection but it may be resistant strain to the medicines they have in the stores. See if they have one without Azole at the end. If they have a vaginal Terbinafine that would work (but if it is only for athletes foot don't use it). Otherwise you will have to get a culture done from the doctor to see what it is. Another thought is trying the Terbinafine spray on the outside (not in the vagina) just to see if it works for about a week or two and if it does then you know you have to get a internal type for the vagina too or anal area. Terbinafine (Lamisil) can be used for jock itch and the private areas so it should be okay.
mkh9