Anti-PD1 and crazy skin thing 9 zillion and 1....

Ever since my last infusion of anti-PD1 in September my skin has been flared up and irritable.  The granulomas on my thighs have remained red, hard, inflamed and itchy. Back and arms very itchy.  Bilateral inguinal nodes have remained constant (they used to come and go) with the one on the right measuring about 2cm and the largest on the left measuring about 1.5cm, followed with another of about 0.5cm, and a tiny one finishing out the trio. Vitiligo continues to increase. Just before our trip to California (10/4 or 5), during a very itchy flare on my back, I noticed a small circular patch of dry skin just below the scar from my initial lesion.  I completely forgot about it during our vacation.  But, when we returned (10/15), I was very surprised to feel a lump there. The documentation follows: 
10/15 - 8.1 X 5.5mm smooth, flesh colored, circular, domed lesion in the exact same location as the dry patch below my original excision scar.
10/17 - size unchanged, texture the same, color now = dark pink.
10/20 - lesion remains same color, size now 7 X 5.5mm.
10/21 - lesion now 5 X 5.5mm with a black scab covering 15% of the top edge.
10/22 - more of a scab has developed, size = 5X4mm.
10/23 - 5 X 3.5mm, with surface now dull and a greater area is covered with a scab.
10/25 - 5 X 2.5mm, lesion now mostly flat scab
10/26 - scab missing, flat pink macule is all that remains.
Today - Brent can find nothing more than a flat, ovoid, pink area.

So...what was all that business????  Brent was very worried.  At first he wanted me straight to derm to have it removed and analyzed.  Then, worried about being kicked off my trial, we decided to watch and wait.  Was it one of the lesions that Weber, Ruthie, Brent and the NP already observed...some inflammatory nodule often occurring before more vitiligo?  Was it a met...which I think is what Brent feels it was?  Melanoma mets can be black, or bluish, or pink, or red. I don't know.  It was truly weird and unlike the other lesions was very smooth, at least initially.  The others have been almost like a pimple or a bug bite for the first couple of days, rapidly turning brown and rough...but never with a black scab. Brent worries for this posting. But, perhaps, one day, such documentation will make a difference.  Anti-PD1 is new...and nobody is talking. Given how challenging the last infusion was, I can't say that I'm looking forward to my next trip to Tampa on Dec. 8th for infusion on the 9th...given, of course, that scans are clear on Dec 2. Then again...maybe it's still fighting off cooties and is the only reason I'm still here! - c