I've had one pink "hive" come up on my leg. it's round and it changes in size and color through out the day. it sometimes has a whiter area in the middle. it doesn't itch/hurt. it just popped up. ?

See a doctor: Without the ability to examine this impossible to diagnose, but at this time of year tick-borne diseases are prevalent and lyme disease is one of several possibilities. Go and see somebody soon. The quicker the diagnosis and treatment the better the outcome.

Not a hive: Hives are intensely itchy. If it doesn't itch, it isn't a hive.