Heard noise overhead.didn't see anything. kept walking. felt a quick pop on calf/ankle. small red dot resulted.can a bat bite and fly off that quick?

Most bat bites occur: -@night, and not to a moving large object as a human. Their radar is very capable of locating an insect so they can catch it with their tail & eat them, they don't bump into trees or leaves. If this was not an insect bite it is possible that it was from a bat. Talk to infectious disease specialist for advice. Only treatment is a series of rabies injections. Only 1 case of rabies survival known.

Bat? Go to ER: I'm not a chiroptologist so I don't know if bats can bite & fly off that quickly w/o you seeing them (not unlike Batman, sorry, I couldn't resist). However, due to risk for rabies, best to get checked out (http://www.cdc.gov/rabies/bats/education/). Even if not bat bite, there's potential for infection of some sort eg cellulitis.