I'm not sure if this is related to psoriatic arthritis. There are times when my feet feel too small for my skin, like my skin is shrink wrap. I don't really have any skin issues except for my back. It's not really visible but to the touch it feels like sand under my skin. It can get extremely itchy. I also have lupus among other things. I take care of my husband, a physically disabled Vietnam veteran, who has dementia.