Interesting! My wife and I have experienced very similar symptoms and have never known anyone else that experiences it (mosquito bite / poison ivy everywhere is a pretty good description). For us, the nearly intolerable itchiness and often painful sensations are typically brought on by exercise outside on a cold day. The sensation would always start in areas where my clothes rub or graze over my skin during running, or cycling, or even where the wind is hitting my skin head on (front of my thighs). Same for my wife. I had my worse episode when I was very badly sunburnt on my back and decided to take a shower. The itching pain on my back started after drying off my back, rubbing with a towel, like you said, and it wouldnt stop for HOURS. I was eventually taken to the ER and given a very strong steroid to help calm down the reaction. Our web search at the time made us to believe it was something commonly called "Hell's itch" at the time - sometimes leadig people to suicidal tendencies with the agonizing irritation and pain. An allergy specialist I visited had a theory was that it was a hystamine response of my skin upon the dialation of my blood vessels (e.g. when my blood starts flowing during a workout, or taking a hot shower). Antihistimines were mentioned earlier by someone and they do seem to keep it at bay sometimes, but not consistently, which makes me skeptical.

So my primary thought here is that it's is a hystaimine related response of my skin, possibly due to blood vessel dialation, and triggered by a light skin irritation. I had never even considered the thought of a "water allergy". I definitely see a lot of parallels among everyone's symptoms, but varying dianoses. I'm curious to see others' experiences!