Extreme heat across back, arms, and hands.

[jockbee1]

On the evening of 12/24 I suddenly had raised itchy patches on my right wrist, right hip, neck, and flushing across my cheeks and nose and forehead.  I took Benadryl which helped with itching.   This continued every few hours for the next 3 days. During this time the middle of my back between my shoulder blades began getting very hot.  This was happening several times an hour and often the back of my upper arms would also get hot and my hands would be slightly numb and cold.  This did not happen during sleep.
Current:  The heat on my back has continued since then several times an hour. This heat is very severe and sometimes spreads around to my abdomen.  When it is severe my hands and upper arms are slightly numb and cold and my lips, cheeks and forehead occasionally feel hot.  I use ice packs on my back and abdomen to reduce the heat and this helps greatly.  The heat is felt internally more so than on my skin.  My skin does not feel hot to the touch and I have not had a fever.  These episodes are becoming more frequent and more severe.  
When I am lying down the episodes are much less severe. Exercise makes the episodes less severe.  Outdoor heat makes the episodes worse. I try to keep a fan blowing on me and I keep my home very cool.
I have removed most sugar, alcohol, coffee, chocolate, carbs from my diet and then added them back and this has had no effect.  I have changed the manufacturer of my thyroid meds and then changed them back and this has no effect.