I used to get absolutely punished by the stuff.
The best treatment I found is cortisone cream. You can use over-the-counter, but the prescription stuff is stronger. The best home remedy is an oatmeal bath. Not sure why, but it really soothes the skin. You can pick up Aveeno oatmeal bath at any major drug store, which is probably better than filling our bathtub with oatmeal.
Also, keep it cool (heat and sweat makes it worse) and out of sunlight if possible.