Crankin, good luck with this -- it sounds horrible.
I don't know if it is anything like the saddle sores I get, but I have one particular place in the "t'aint" area
on the left that has twice developed a saddle sore that eventually took me to the dermatologist's for a cortisone injection. But they come up more slowly, fill with blood over and over (yes, I confess to poking a sterilized needle in and squeezing them), and cause excruciating discomfort on the bike. The cortisone shot nips it immediately.
Yours sounds almost like a bacterial infection, a true boil. glad you're getting it checked out, and let us know the results.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow