odd rash

grrls, need your input on this. Did my first century yesterday in hot and humid conditions. I felt fine during the ride (well, sort of!), but after I took a quick post-ride shower before getting on the train home, I had an incredible rash with welts on any area of my legs covered by my shorts, but particularly on the front of my thighs. The rash and welts have calmed down considerably but are still visible. It doesn't hurt *at all*. I've had these shorts for years, haven't changed detergents, soap etc. The only thing I can think of is the effect of having the shorts on for such a long time in such hot, humid conditions. It definitely is worse around the areas where the elastic was on my thighs. Has anyone ever experienced anything like this? As it doesn't hurt and is subsiding, I'm not too worried, but curious re the cause.

I seem to have a different kind of rash all over my butt, but I'm assuming that is just heat rash. Speaking of which, what's the best way to handle heat rash? It's only mildly uncomfortable and I'm wearing loose natural fiber pants today. Is that enough?

thx!

I swear by Gold Bond powder. They also have a Gold Bond cream but the powder is great.