I have dealt with Pox a lot, sadly. That is not Pox. It would never be just one digit and there would also be pox bumps in the genital area, all 4 feet would have all of the toes swollen. Also it doesn't look that color.
I've attached a pix of one of my squirrels (who survived) genital area. These pox lesions at this area appeared at the same time as her swollen digits and eye bumps.