Hi,
General advice would of course be to see your dermatologist soon. Your descriptions may be extensive, but an
inspection by a trained eye may see much more.
Some features that raise doubts that this is cancer is the location which is not exposed to light. Any area
with a previous swelling may turn dark and resemble a mole.
Some features that raise suspicion for malignancy include: asymetry, irregularity of borders, and nodularity.
I'm uncertain whether you were referring to a Group B Strep infection or Guillain Barre Syndrome, but
neither has a causal relationship.