I have been getting red itchy welts on my hands, arms, shoulders, legs and they are getting worse. This started last October. They seem to come from any type of medium to heavy pressure... Like carrying a heavy grocery bag, kneeling, carrying books or lots of papers at once. I am a teacher. Benedryl cream helps, but it is getting very annoying having to stop and put it on many times a day. What would cause these pressure hives?