I've asked this question on a few forums before, but never on UKC so thought I'd have a go.
I've had this issue for about 20 years now, where when I run, I start getting a really bad itch. It starts in my calvs and thighs, and works it way up to my gluts and waist. If I ignore, it gets so bad it reduces me to a heap on the floor almost trying to peel my skin off. Itch is probably the wrong word for it at that point. Pushing through it is not an option.
It appears to be something to do with vibration. The impact from running. When I used to cycle, I got it a bit on my arms on bumpy routes through the handlebars. Sometimes when I'm particularly inactive, I get it form walking on a high street, however, I find staying active mostly keeps this at bay.
I recently discovered that I don't get it hill running, I believe because running up a hill has less impact. Although I'm not entirely clear why hill running doesn't appear to bring out the effects. Even after months of hill running, still can't run on flat ground.
GP's don't know what it is. I've had blood tests with nothing unusual coming back. They don't know what to do with me after that.
Anti histamines don't work.
Building up a tolerance doesn't work. It helps a bit, but takes months to build a small tolerance (very small) which can be lost in a week or two so not sustainable.
I've tried elimination diets, with a focus on alcohol, coffee, eggs etc but couldn't find a relationship.
It may be slightly worse when cold, but not clear on that. Possibly also worse if tired.
Plenty forums out there with lots of people suffering the same thing, but none have any answers.
Long shot, but anyone on here suffer with this issue and have a magical solution.