Pyoderma Gangrenosum

Can anyone please tell me how PG comes on and its stages after that?  I think I have the beginning of an ulcer, but my internist (bless her heart, just doesn't know much about CD) - it's an angry, purple, inflamed cyst on my left side (my waist, right where pants hit it) that's about the size of a nickel. I've been on 250 mg of Imuran for almost a year and off/on varying doses of prednisone for about the same time period.  I've been in the midst of a moderate-severe flare for quite awhile now, and last Friday, I had an "episode" of severe joint pain, around 25 BMs - watery diarrhea - in about 3 hours - along with massive upper and lower abdominal cramping, and lower right quadrant pain (that's where my disease was first diagnosed 20+ years ago) and a low-grade fever.  Saturday night, I noticed this cyst because it hurt to turn over in bed.  I would speak with my GI about this, except he's unavailable, and I have to go through my internist first, anyway.

So, I'm a little concerned that it might be PG - hope it's not - but if anyone out there could shed some light on it for me, it will be greatly appreciated.

Thank you.