could be a bunch of things including mold or nastys attacking the residue from your last session.
I would season it again real high temps and clean er out. Then reseason. You could bring it up to temp with a water pan above the heat source to "loosen" things up a bit. Then when it comes down to manageable temps hot water soap and sos brillo pad rinse and reseason er.
Possible post a pic of it for a better understanding, folk around here will know what to do.
good luck and get er back in action