For me a flare ( which i have been experiencing this past week) is the terrible burning pain and redness and swelling in my RSD foot and leg, and then the burn starts in my right foot and leg, and my face and mouth burn....and I get very, very cold and dizzy.
What a combo ...the burn and the cold...

It could be a variety of things.....

1. the monthly shots that my foot doc administers directly into the nerves have worn off...

2....the warm pool aqua therapy ended, ( insurance...)and although it would aggravate the nerves in my limbs, it kept the swelling down...the edema is really bad in my RSD foot right now, to where if I push down on the skin, it doesn't bounce back up (ya know, like it does on the Pillsbury Boy...)

3. I cut back a little on my Neurontin, because it was making my brain feel like a bad foggy day in San Francisco.... forgetting words and losing files at work....and the weight gain is awful...

4. my worse fear is that the RSD is getting worse...

Hope4thebest