You are experiencing a run of not such good luck. Hope it is at an end!
I don't know anything about chiggers all I know is it hurt a lot and I hope you're right!
This is very unusual; don't let it dissuade you from orienteering in the future in QOC woods. Chiggers aren't fun but your reaction would be extreme if that's what caused it. Usually you don't feel any bite from them.