In my case my RSD spread from the orignal affected limb (My right leg) to my left leg, so YES it can definitly spread. I have found that when you have RSD, half of the battle is getting your doctor to listen to you. I would insist on getting an appointment with the physican that treats your current condition. Also, half the time nurses just say stuff and maybe this nurse did not tell your doctor your newest concern. Call again and tell them you must talk with a doctor either by putting the message through or making an emergency appointment. With this disease you can never be too careful.