The area in the blue circle is where the last episode of this stuff was. That shows where the skin will eventually dry down, crack open, and eventuall flake off. I teach in a public high school so it's possible to come into contact with everything known to man and a lot of stuff that hasn't been discovered yet! It's amazing how nasty some humans are and don't care about being.
None of the 15 doctors I have seen have mentioned any parasitic cause of this. This all goes back to a blood blister I had on the side of this index finger last summer. A shot of K-40 Antibiotic usually will dry this stuff down, but it always seems to resurface when I get a break in the skin where it has been. The doctors have had me on three other Antibiotics , but I have given up on them because they just don't help the condition any. I'm beginning to have serious thoughts about having this finger amputated to get rig of this stuff - I'm diabetic too and something like this that interferes with the circulation ain't good for me.