Don't forget that as you lose weight, you also lose your own insulation.
I used to be the person walking in the snow in a t shirt, now since I lost 6 stone with band I am cold all the time, i'm now the person with a cardie on when everyones in t shirts...
Remember it takes your body time to adjust to this weight loss as well as your mind, but don't rule out being poorly first...hope you feel better soon xx