(coming out of lurk mode because this hit so close to home)

I had a similar painful boo-boo in the same area last summer. I thought it was an infected hair folicle. Then I thought it was a saddle sore. Then I thought it was the batholin's gland...so I went to my ob-gyn. It turned out to be a blood clot/vericosed vein. She gave me the option of lancing it in the office (basically slicing it open, removing the clot, then letting it heal...6 weeks out of the saddle), or applying hot-as-I-can-stand-it wash cloths to the area, then using a sterlized needle to work the clot out myself at home. I opted for the home method. She checked it three weeks later and it was much better.

My doctor thinks it vericosed because of all my time in the saddle preparing for my first mountainous metric century. I have the bad habbit of leaning forward on my saddle when I climb, and there is a vein running between my saddle and a ligament/tendon/whatever right there at the panty line in front of my sit bone. Over time the ligament rubbed and compressed that vein against my saddle and created a monster, marble-sized boo-boo.

I have since traded seats on my bike. It is much firmer than the old one and I haven't had trouble with that area since.

Sorry this is so long, but perhaps it will help.