I think sometimes we try to use our injured parts too...typing at work etc.
Maybe accidentally resting it in an odd way. Circulation etc. If it's your foot, maybe twisting it under a chair etc.

I know after I get out of Orthopedic Therapy later that night I'm on fire or I feel my arm is even heavier and more difficult to get comfortable.

Although I'm not sure, no one has diagnosed me with RSD. I'm just swollen and in pain with no answers darnit!

I went to CVS and purchased a moist heat pack, it seems to help when things get chilly and messaging the area after I apply it seems to help a little bit. Perhaps it's worth a try for you?