What Causes Rash On Knuckles And Elbows Along With Patches On Arms?

Hello, Every Spring and Summer I get a rash on my knuckles, in my elbows, under my knees, and occasionally in patches all over my arms. The rashes are made up of tiny bumps filled with clear liquid, or raised patches of rough skin. They itch terribly, but do not become too discoloured on their own. I have been using hydrocortisone cream on it, but it doesn t seem to do anything. What could this be?