I have not had a client with ringworm. Did you let the client know about that? Did you sanitize everything good? It is a fungus and is coneforum.xxxious, though I don't know to what degree. She/he may need medication, and you should wash yourself and your area with tea tree oil or other antifungal wash.
There is also the possibility of Lyme disease and a few other things that have that "bullseye" look. Even without the target in the middle, it could be. Medical attention would be prudent.