Ugh, I'm sorry to hear of your misfortune, FoggedIn.
I'm really hoping that these symptoms you're feeling are just a product of your over-stressed mind and emotions, and nothing physical. I could just smack these guys upside the head when they think with their d*cks and drag home their diseases to innocent spouses. There's a special Hell for men like that.
First and foremost, cheaters lie. They lie, lie, lie and deny, deny, deny. So the chances are extremely high that you haven't been given the truth - about any of his past transgressions or what may have really happened with this latest Craigslist whore. Ugh.
I would ABSOLUTELY require a poly from him as part of a possible reconciliation attempt. I read a lot here about women who have scheduled their husbands for a test and some have refused to go, some have claimed they feared a "false positive" or that poly's "aren't an exact science," and blah blah blah.
But the way I see it is how it affects them psychologically. Knowing they'll be tied to a machine and every move they make and every breath they take being monitored is pretty damned intimidating - regardless of how savvy a liar they think they are. THAT'S the advantage to scheduling a poly - bringing them down a few pegs and humbling their lying asses down to where you just might get some truth out of them.
I've read past stories here where the husbands (or wives) have done an internet search for "how to pass a poly test" so don't be surprised if you see THAT somewhere in your home computer's history (if he doesn't have a computer at work or cell phone he can search on without you knowing, that is).
Lastly, just KNOWING they're going and will possibly be exposed for lying in front of a stranger and then you being told about it is humiliating and demoralizing, and a lot of them will give you what's called the 'parking lot confession.' That usually occurs the day of the testing - on the way out to the car to leave for the poly (or in the poly parking lot itself), they'll suddenly break down and confess to something they hadn't admitted before. Some of them are devious enough JUST to give you a tidbit of truth that you didn't know, in the hopes that you'll cancel the test thinking you've finally gotten it all.
Chances are extremely high that you STILL haven't gotten the whole truth. A smart BS will appreciate that little parking lot confession 'tidbit' they squeezed out of their cheating spouse but STILL go ahead with the test.
There's always more. Always. It's very, very rare to get 100% of the truth.
I highly advise you go forward with this as quickly as possible because if he starts believing his own lies (and some of the actually DO start believing their own crap), then they won't show as deception on a poly test because he'll believe he's telling the truth. Ugh.
Google "polygraph testers + your city" and start looking at what's available. I think the median cost for one is around $500.
Good luck to you FoggedIn.