Flares are different for everyone, and mine vary too, but I'll try to describe the best way I can what they felt like to me last night.
It started with a deep aching, burning pain in my stomach which got increasingly worse over the course of a few hours. It feels like aching and burning from the inside out. Then the pain spread to the my limbs. (My arms, hands, legs and feet.) That pain feels like a deep aching cold pain in my bones and then a burning electrical like pain. That burning pain makes it so bad, that even putting a sheet on my skin hurt. It can last for me from hours to days, but "luckily" last night it was only a few hours. The meds help numb the pain. The combo of neurontin and percocet help me with that. If I didn't have those meds, I don't think I would be able to go on. My hands hurt so much that even picking up the remote for my tv hurt and my feet hurt if I tried to stand. And on top of that my Fibromyalgia caused more pain too. It made all of bones hurt if the slightest pressure was applied to them. The bones in my ribcage and feet hurt the most last night because of this. And then the acid in my stomach got worse and caused burning and nausea. My rsd hand felt colder than my other hand and started spasming. It felt like everytime I typed (even though I didn't type that much ) I started getting a vibrating, burning pain that increased the more I typed and then it started cramping up and got really cold. And my fingertips hurt when they push on the keys and the mouse.
I had to stop and go lie down because of all of this. Lying down seems to help sometimes. I find too that when I'm having a less painful day, that I try to do more and then pay for it for a few days after. The pain increases ad I can barely move. Well I hope this helps and that you feel better soon so that you can enjoy your day.