This is the second time we've tried potty training. Both times, my boys have gotten rashes on their bottoms that weren't there when they were in diapers. The underwear are washed in the same detergent (free & clear) that I wash all their clothes in. The first time I wandered about it being from the little potty seat, but this time it started even when they were just sitting on the regular toilet seat. It's all over their bottoms, so I feel like it has to be something with the underwear.

Any ideas? It's making them not want to sit on the potty, which is a little bit inconvenient right now...