It's all nerves my dear. When I get a severe panic attack I wake up the next day shivering, my legs get very heavy, I can't stand noise, bright lights......your body is under a great deal of stress when you are anxious and it takes a lot out of you. You feel literally 'ill' all the time but it's all anxiety.
I can totally relate to that cold feeling! I have it too. I get it almost everyday. Then right after the feeling my hands start shaking. I got very scared the first time I ever felt it. I thought I was going to die. It is a very scary feeling. I went to the ER one time thinking I was going to die but the Dr. said it was all anxiety.
If you got checked out by your doctor, then I would believe him/her. Anxiety can cause all sorts of symptoms...especially health anxiety. When I was going through this, if you could name it, I thought I had it, and every little twitch, pain, sensation was a huge call to alarm for me. In my opinion, quite often this cycle of thinking can really get us trapped into believing that we have something truly wrong with us when in fact we are suffering from anxiety....have you had anxiety issues in the past?