It's usually in spots where my skin is the most fragile and sweats. Like, behind the knees, behind the ears, armpit areas, stomach, behind the elbow, eye lids, inner thighs etc. I've started using aveeno eczma cream and hydrocortizone and it has helped reduce redness and smoothed out the skin a bit.
I started using the Joye 510's back in 2009. I used to get itches on the top of my feet, but figured it was due to sweating and my socks. I started vaping again maybe less than a year ago and have been using the ego twist with cartomizers... I started getting dry skin and minor itches, nothing serious. My hives started breaking out bad when I got into DIY and rebuildable atomizers. My guess is that my body couldn't handle that much PG (or some type of chemical) since I started chain vaping since then and I was vaping 3-4x more than before. Also, my room would get much more foggier from the large amounts of vapor I was producing with the more advance mods.
I've switches shampoos, soaps, laundry detergent, washed everything etc. The only thing I can think of is from vaping and I'll find out in about a week to pinpoint exactly what is causing this. It's just extremely weird how when I read other threads about this they're experiencing the same thing.
It really sounds like you have psoriasis. You can't get it from vaping- it is genetic, and sometimes doesn't appear until someone is in their 20's. Nicotine can make it worse.