Things have improved a little bit on my arms today, aided by a dip in salty sea-water. I'm still not sure there's not a flea or some other little creature active on or under my skin. There's an extra finger that's gone itchy and an inch-long weal across the back of my hand.
I've used a cream called Eurax to soothe the itching, which is still terrible around the weals and welts. Even if they stop itching, a single touch starts them up again. The cream leaves the skin all red, which seems worth it, although I fear it may be aggravating the problem. The spotty rash in the cradle of my elbow seems to have gone.
I am trying to avoid insects.