Psoriasis and Hives

Hi, I had a particularly bad outbreak of guttate psoriasis at the start of the year. Managed to get rid of this after about 7/8 months and using Dovonex. In August I had a really bad outbreak of inverse psoriasis on my neck which I managed to get rid of with Dovonex after about a month. Recently, any time I get stressed, too hot, wear something tight around my neck(even just a normal hooded top) I get big patches of red skin on my neck that seem to disappear after about 2 hours. I've been to the GP and been told to use antihistamines which don't seem to be helping too much. Has anybody ever had any experience with hives after a bad psoriasis outbreak? Any advice/insights would be useful. Thanks :)