Secondary Rash

In early January, I noticed a darker area on my side upper ribs.  I had to look twice to ensure it was not an old scar from when I had shingles when I was 12.  I rechecked it in a week and it had grown again to twice its size, now 3-4 inches oval.  It was not painful, itchy, splotchy, or raised- just a darker color.  Another week passed and it was still there, but now with a lighter center.  It really looked a lot like my original bite rash, except for the center bite mark.  There has been no other accompanying symptoms, except occasional eye twitching, light random dizziness, night sweats, and some fatigue.  That is, other than some pain at the original bite site when sleeping on it, or walking after sitting for a while, like after driving or getting up in the morning.  I am taking Bone, Joint, and Cartilage supplement for my hip and it really makes a difference.  Thinking about calling to see if I need to be retested since I obviously did not get re-bitten this time of year.