Can you have complex regional pain syndrome without pain? Someone I know has been diagnosed with complex regional pain syndrome, and has all the symptoms - but isn't experiencing any pain. What could possibly be occuring?

CRPS. The main character of complex regional pain syndrome is pain. I'm not aware of complex regional pain syndrome without pain. I recommend you see a pain specialist for evaluation.
Ironic. How was crps diagnosied without any complaint of pain unless there was pain previously. Sometimes crps "burns out" leaving mostly the degenerative changes. If this was newly diagnosed, i would also consider circulatory problems or diabetes as suspect. There is also the remote possiblity of some sort of central nervous system disease like ms.
It . It is hard to answer this without the details, but with crps the fact is nobody can give you great answers anyway. I will assume you mean a doctor has diagnosed it, and that the patient has other symptoms such as edema, blood flow changes, and abnormal sweating, as well as a known injury that produced these symptoms. If that is the case, nobody knows what causes crps, and i can only say your friend is very lucky to avoid the pain, which is clearly the most annoying part of the disease in most people. However, the other possibility is that it is not crps, and depending on the symptoms there could be other things going on. If the diagnosis was not made by a reliable physician, i would seek a second opinion.