Problem with rash on legs. can anyone help?

i had a red, bumpy rash starting on my legs in september then it ended in about november.it started again in about april and it isn't going away! it spreads all across my legs in little bumps. its really gross and some look like whiteheads. it didn't help that i had to sit on sweaty chairs because i started getting a really bad heat rash on my thighs. it spread to my butt and now i can't wear anything but long pants in public without revealing my legs and the bumps. any suggestions? should i see a doctor?