I always get that rash equally on both legs. Some DISers have correlated it with sun/heat being reflected off the ground. I was determined last week to get to the bottom of the cause at least for me. When I get it, it is immensely uncomfortable and very unsightly.
So I bought the Premier Pass for MK to test out a theory and bought LLMPs and SP's where available. I normally would never purchase a Premier Pass but I have other health problems and just didn't want the rash on top of those.
So what I did for the first time is not walk incredibly fast to attractions during EE and I just slowed down by about 25% in general and I swear that was a major contribution to preventing the rash. Yes, it meant that I had to sometimes wait a little longer in lines but LL was a great help.
Premier Pass- I was overly optimistic about how my day would go. It was anything but predictable. The cost of PP was $500+ after tax. I arrived for EE because I wanted to do Peter Pan twice. I tried to get first to the rides that could close during afternoon rain. That went okay but at park open, Tiana and SDMT were down. I traversed the park many times all day trying to see if SDMT would open. It was down all day but finally opened in the evening I heard, but I had left. The beauty of PP is that I didn't have to rush to attractions and that was my test. The negative is the PP works well if all the rides are working well which they all weren't. I started adding up the cost of each ride by dividing up the $500. I couldn't help it.
Conclusion- In the past, I would almost be running to attractions, especially early on. My doctor saw me right after I returned home last year and the rash was in full bloom. He said race walking and the heat combined, started me on the road to the rash which he called vasculitis. It was his suggestion to slow my walking down, drink lots of water and *** whenever able, find an indoor seat in a cool place where I could elevate my legs and get proper circulation moving. I did all of those things. I believe it helped.
***Don't forget that if you are experiencing a serious problem, the first aid stations are equipped to help you manage it. I know because, I got heat stroke at AK and they were fantastic.