What do you think bit me?

I had a horrible fever, sweating like mad and then freezing the next minute.  Extreme dizziness and nausea over the past few days and in a drunken-type stupor, reaction time slowed waaay down. If I turned my head quickly, took a while to focus, felt like the world was spinning, felt like I was drugged.  I could not even drive, it was that bad.

In addition, I had an odd red circle on my thigh with 2 distinct little fang marks in the middle.  The area around it was hard and hot.  Coincidence, or do you think this might have been some sort of spider bite?

A little background - my oldest son had a horrid spider bite reaction a few months back (in another state so probably not the same spider unless this thing is following us around) - it landed us in the E.R. and they had to scrape away a bunch of his skin - but they said that it was not the actual venom that was the issue - it was HIS skin's reaction to the bite.  He was quite lethargic through all of it as was I, but with the delayed reaction time and all - does that sound more like venom?  Like the spider's natural weapon/ technique to slow his prey so he can come and eat you later?  

I'd just like to know if this is simply how I (and my sons) react to spider bites (if it was indeed a spider), or if was a venomous bite.  If the latter, I need to find this creature and do away with it before it gets someone else.  Thanks.