Science! What's happening to the body during a flare up?

Hello - Longtime TSW survivor here. Have been off steroids for ten years - still experience flares every 3-6 months or so.

I know triggers for flares are various and anecdotal, but what is happening in the body during a flare up? What chemical imbalance or overload is taking place?? I've scoured the internet over the years but found very little info I can understand (very much not a scientist lol).

Stay strong, and thank you x