If you've been having a lot of ct scans it could be an allergy to the dyes.
I came up in tiny pustule blisters on my hands and feet but these useless doctors didn't seem to mind since it not life threatening only itchy and hot.
I took telfast and it was useless and since my hands were so red looking I tried Nurofen as an anti inflammatory. It worked! The red was gone surrounding the blisters and the itch abated. Days later I have lost the skin layer on 3 fingers as it just dried up and came away in one piece.
My two ct scans were within 18 days of each other which is probably why my body tried to get the dye out in some other extra smart way, through the skin.