A few days to a month before you have other symptoms, a small, red bump may appear at the site of the tick bite
. Over the next few days, the redness expands, forming a rash in a bull's-eye pattern, with a red outer ring surrounding a clear area. The rash, called erythema migrans, is one of the hallmarks of Lyme disease. Some people develop several of these rashes, an indication of bacteria multiplying in the blood stream.