hi leggie. i'm sorry you bumped your rsd limb and understand how scary it can be for fear of spread. with time you will learn what rsd spread is vs. a really bad flare up. even drs don't always know and that's where learning to listen to your own body comes into play. it could be that you are just having a really bad flare up because you bumped your arm so hard and it may subside with time. if it is spread the pain will probably continue on and not stop and you will have physical symptoms though maybe not as significant as you initially had with rsd. some symptoms may be increased swelling, redness, excessive hair growth on your arm, trouble moving your arm, temperature changes and above all increased burning pain. you may also have something else and may want to have dr check for a fracture by taking an xray. i am not a dr but am just explaining my experiences on how to tell the difference between rsd spread and rsd flare ups. whatever it is try to stay calm because stress can add to pain. you may find that in a few days your symptoms may subside. if not it could be spread but if i were you i would then confirm with a dr and xrays. usually with rsd spread it is something you just know immediately where with flare ups you don't. that's my rule of thumb anyway during the past five years of having rsd. i hope it is just a flare up from the bump and that your pain eases soon. sending soft hugs your way.