I started reading this post because I have this problem too. It just started turning cold and boy could I feel it. I usually have this "I'm always cold issue" starting in Oct.
I keep myself toasty at night.
After many years I figured out I have Lyme along with a bunch of other parasites and bugs.
I've been treating myself semi-aggressively since Jan and have made great strides. I'm impressed at how persistent these bugs are. SUPER PERSISTENT.
I do a million things... but I noticed my temperature issue got better since getting better overall.
I do everything that was on that great list put together by one of the folks... except for kelp (haven't tried that yet).
It takes a while body approach. If you feel that things don't get better you may look into Lyme through http://www.igenex.com
My sibling may also have Lyme too and she tried a parasite cleanse and didn't notice any difference. She eats super clean... kale, chea seeds, organic, herbal teas, etc. so I know something else is up besides a recent parasite infection.
The problem was she wasn't addressing it aggressively from multiple angles because she thought she just had some minor parasites... I think it is Lyme and co-infections PLUS parasites and CANDIDA and all that junk. She wants blood work confirmation... I was the opposite. I wanted to start getting better asap.
You may have to do a dozen things at once to start getting better... I know it sounds crazy but this is needed for that and that's needed for this... etc. So one thing needs another.
Body temperature is something I'm still working on. I tried all the things mentioned and they are baby incremental steps... it's not like BOOM you get better. It is like work, work, work, work and after four month you notice a little change :) and then again after six months.