[sammyg2]

Iffn it's a black widow bite it should have gone away by now or at least started to go away. If it's from a brown recluse, get medical attention yesterday. Lots O'bad things can happen (like in that picture).

A few years ago a young woman got bit by one, she ended up loosing both arms and legs.
The flesh just dies and keeps rotting, getting bigger and bigger. Without the spider they may not be able to identify it but better safe than sorry.