Recurring Bumps On Thigh, Itchy. What Is It?

I have had raised red areas on my mid to upper right thigh on and off for over a month. I usually get one at a time, it goes away, and then I get one in another spot, but they do reoccur in the same spots. Initially I feel a itch, and then a raised bump appears (usually with a few small blister like bumps inside or one big one) and lasts for a few days and very slowly fades away. I always have at least one though since I first noticed the rash. I do workout quite a bit, so I thought maybe it was just from sweating.