I have a rash on forearms & thighs. Skin colored, slightly pink. Not itchy. Small bumps all over, not patchy. Possibly allergic reaction to z-pack?

Many possibilities. This could be a reaction to a z-pac , a new food, or some other exposure.I would hold stop the med for now and contact your pcp in the am. S/he may want to change the med or have you evaluated.This med is going to be in your system for a while.So more rash may continue to come up for some time.
See below. If the rash is new since starting the z-pak, it is probably a reaction. Stop it and call and let your prescribng physician know.