Hi,
Have you double checked your temps? Overheating can cause similar behaviour - as can certain types of parasites IIRC.
It really might be worth putting an apointment on at the vet - if you manage to find the cause before then you can always cancel.
But January is a fair bit away.
You havent been exposed to any chemicals or anything or changed anything in his enclosure? The place you get feeders isn't treating for mites or anything?
Just trying to think of anything you could rule out - the vet will almost certainly ask anyway.
I hope your guy is ok.
dr del