How can i get rid of this rash?

ok i play tennis in the summer now and i wear spandex under my skirts and stuff. when i run they roll up under my leg and i usually have to pull it out. thats understandable. but for the past two days, ive been almost "burning" between my legs everytime i walk around with my spandex or at all. its hindering my preformance so how can i get rid of it. its red and bumby and hurts to touch. HELP?