Cellulitis is the diagnosis, where the seat contacts the body. Inflammation, fever, discomfort. Did this come from a 600k brevet two weeks ago? No. From unicycling 12 miles last weekend? No. It's from the new saddle I put on my commuter, and my 1.5 mile commute. Amazing. I guess I'll be a pedestrian and motorist for a few days. Searches don't show this as very common for cyclists, but I've had it twice in the last year - both times after switching saddles.