I'm assuming you mean your inner "thighs." It's hard to say what the cause is without seeing them but a few things could be chaffing, which is the rubbing of your inner thighs, exzema, an allergy/intolerance or infection.
Have you tried aloe vera gel? Make sure it is pure. Aloe vera is a miracle for all sorts of skin ailments including rashes, burns and acne. Apply this liberally for a day or two and you should notice improvement. Don't scratch or rub as this only irritates the skin more.
Hello,
It can be due to 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.