Thats from a flying bug.. One you'd find in like the rain forests or africa... It like stings you with its butt and sorta craps its baby into you as it so on so called "stings"you. The whole time it grows from egg to larva its feeding off blood and then eating the meat underneath you're skin. I seen a picture once of a guys arm that was covered in those things..

And HE WAS STILL ALIVE.!
I've had nightmares about that type of bug..