Could be the beginning of a saddle sore. Not good. Sometimes, washing itself is not enough, you have to be very very careful to dry completely after your shower. I know of one guy who sometimes uses a blow dryer to dry down there. The reason is that, unless you're using anti-bacterial soap, it's very difficult to get rid of all of the bacteria that can build up from sweat. Leave the area damp [and warm] and you have a perfect breeding ground for wee beasties.
For your immediate problem, get some kind of tpical zinc oxide preparation like Ihle's Paste or even the diaper rash ointment of your choice [a saddle sore is just diaper rash on a cyclist] and apply generously for a couple of days.