body on fire - reaction

It always starts with my ears.  they both get very hot and then turn bright red.  It moves down to my cheeks, then my arms, across the top of my chest, then my legs.  I look as though I feel asleep on the beach without sunscreen.  This only occurs on the front of my body, and does not occur on neither my chest, nor my stomach. (again, as if I feel asleep on the beach in a bathing suit)  The heat that radiates off of my body is intense and can become painful if not caught early on (like while sleeping).  Once it begins to subside, I get the chills really badly throughout my body (again, as if i had actual sunburn).  The whole process usually takes an hour.

A few things have been confirmed\defined:  
1.) it is allergy related because Benedryl will halt the reaction and make it subside  
2.) This started in June 09   (I started allergy shots around the same time and was having bad reactions)
3.) It seems to occur sporadically, without common markers.
4.) I did not have any occurances in September & October. (but was still getting allergy shots)
5.)  I have psoriasis & psoriatic arthritis, but am not currently being treated.

Doctors have me getting multiple tests, but still no direct answers.  I hope someone can share some insights and/or ideas.  Thanks.