A Few Days Ago I Developed A Bilateral Itchy Rash

A few days ago I developed a bilateral itchy rash on my outer thighs. I am not prone to rashes & do not have any allergies. I'm not using any new detergents & cannot think what may have triggered it. I don't usually take antihistamines as some give me heart palpitations. I'm able to get relief by icing the area but the rash persists. Will see my Dr. on Friday but would welcome your input. Thank you!