Purplish Rash on inside of legs/groin

I have had sort of a purplish rash in the inside of my legs and groins for over 6 weeks now. I have some stretch marks and they have become purplish. At first I tried over the counter creams and sprays and they seemed to calm the symptoms. They did not go away though. The doctor prescribed me lotrisone cream and I have been using it twice daily for about a month. Again the symptoms go away but the rash has not. I did have fellatio over 2 months ago but a condom was used, the condom was removed and she had some spit on some of my penis . That was the only sexual interaction I have had in over 5 months. I had gotten a sore throat last week, but antibiotics helped take care of that.  I am starting to have some extreme anxiety everyday the rash does not go away. I am thinking of every possible worst case scenario. A few questions am I overreacting? am I overusing the lotrisone cream? Should I see a dermatologist? Would I be at risk to any type of STD after my interaction? Please help.. Thanks

[Bhupinder Kaur, MD]

Hello,
From your symptoms I would like to rule out lichen planus. Lichen planus is an inflammatory disease that affects the skin and the oral mucosa, and presents itself in the form of papules(flat spots) or rashes. It is an itchy papular eruption characterized by its violaceous color.

Treatment is available only on prescription and consists mainly of steroids, retinoids, hydroquinone and phototherapy. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.