OMG, I go from sweating to chills in a matter of a minute. I too am in my early 50's, SE Florida, so I do attribute some of this to those two factors but it seems to be getting amped up.
I've noticed other people complaining about this too but it's hard to tell if these people just like kvetching opposed to being a real issue.
But I'd say it's gotten real bad or uncomfortable the last 2 months and...getting worse instead of better. After all we're theoretically in winter (well, on the 21st) so the heat is behind us although...it's still uncomfortable out there. I've had my AC on for 3 days now.
My change started 3 years ago. So that too should be dissipating not exacerbating.

I just don't know anymore what's me, what's natural or what's 2012-related.

I thought this was supposed to be a 'great time to be alive'???
So far I cease to see that.