Update: I believe my bump is a spider bite.
How are you doing now?
Spider bites can get nasty, so keep an eye on this. If it starts to feel warm to the touch, or the redness around it starts to grow, see your doctor promptly. If you get nauseous or get a fever, go to the emergency department at your local hospital.
It would have been useful to know how big the bump is, and how bad the redness and other signs are. If it's small and not very badly inflamed, I wouldn't personally worry about it much - though I would remember this if any odd symptoms develop down the road.