Hmmm, I'm just remembering that it was almost exactly 2 years ago when I had the mystery hives. They were on my knuckles, knees, tops of my feet, and all around my hips/thighs/butt. Maybe my elbows too, I don't remember. I wound up going to Urgent Care after a few days because it just kept getting worse. The doctor gave me an Rx for steriods which cleared it up, although she wasn't able to say what caused it.
At the time I thought maybe I was allergic to blueberries, which I put on my waffles with breakfast in the summer. But after that rash cleared up I was able to eat blueberries again with no problems. Anyway it's that time of year again and I've been buying and eating blueberries for the past couple of weeks. I wonder if there's something about late June/early July blueberries that I'm allergic to, like a certain pesticide or other chemical used in some regions but not others.
Or maybe not... 
I'll probably never know. Anyway, I will not be eating any more blueberries for a while.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles