What Causes Scabs On Arms, Back, Chest And Hands With Dry Skin?

I have red bumps/scabs on my arms, back, chest, and stomach. Also, on the inside of my hands get very very dry and the skin breaks open making painful and irritating cuts. I have been struggling with this for awhile now but it keeps coming back. Sometimes the inside of my hands and my fingers get really itchy and i itch them until my fingers are swollen and red. I went to a doctor last summer when it was horrible painful and itchy ALL over my body and was perscribed to prednosone? which was a steroid that made me gain alot of weight but cleared everything up. I'm wondering if it is psoriasis and if i can use lotion from a drugstore to clear it. Right now i am only using Aveeno anti itch fragrance free lotion for extra dry skin.