Wow what a lightbulb moment for me. The term "Golfer's Vasculitis" caught my eye.
2 years ago I returned to Alice Springs to play golf in the Masters Games, having moved away from there in 2011.
First round of golf was ok, on the second day I had this nasty rash which felt like bad sunburn initially, a real burning. Missed the third day's play, my feet were swollen and I couldn't get the golf shoes on.
On the final day's play it returned with a vengeance. I changed into long cotton pants halfway through which didn't help. My last couple of days in Alice were spent wearing jeans in the 40 degree heat to cover this up. It took about 5 days to fully resolve. You can see how puffy my lower legs & feet were.
From browsing a few articles which came up in my google search, it seems the worst area is usually the inner calf, just above the sockline.
All this time I thought it was a reaction to fertiliser or something on the golf course. A very faint patch had started to appear on one arm as well.
At least I have a name for it now, thanks Callie