You should get it checked out by a doctor.
I have had a spider bite that leaves a small boil, but if it's left unattended for a week, it will slowly grow in size. This boil always has pus in it. I live in Nebraska what type of spider is this?
Are you sure it's a spider bite and not just a boil? You may need to see a doctor and have the area drained and properly cleaned.
Brown recluse or a hobo spider most likely. Brown recluse won't kill you but a hobo spider bite can be fatal if not treated correctly.