I had hives last winter, at the end of the "wool" season; they appeared mysteriously after a few years of no problems with merino. I've had a history of hives, weird allergies, asthma, so while not unusual, the fact that the wool started to bother me all of a sudden, was weird. Someone here on TE suggested the Zantac, combined with Claritin, and it worked right away.
NY Biker, I feel for you. I have gone through several bouts of what you had and it's scary and annoying.