Itchy rash on fingers?

F23 (164cm, 67kg). I don’t smoke. I take 40mg cetirizine, 60mg famotidine, 4mg ketotifen a day, Xolair 300mg every two weeks, all for MCAS.

https://imgur.com/a/sAXgVed

Two weeks ago, I suddenly had a strong itch on my index finger. A red patch developed there the next morning, but it wasn’t itchy anymore, but sore to the touch. Four days later, the same index finger started itching again, and another patch developed above the joint. Since then, it’s been itchy at times (usually during the night), and usually when my mast cells are reacting to something.

These past few days, my index finger has swelled, the skin has broken, and my thumb on the same hand has started itching too, and the skin just below the nail has become red and swollen. It doesn’t itch right now, but it’s sore, just like the other finger.

I thought it might’ve been some kind of urticaria, since it seems to itch when I’m reacting, but urticaria doesn’t usually last for two weeks, does it? And it’s very localized to those two fingers. I don’t usually get much urticaria during reactions.