My neurologist diagnosed the CRPS in my left ankle/foot/leg, after having gone through several steps. He reviewed the nerve conduction study performed by a certified neurologist from my prior medical group. Also reviewed the MRI of the area because the foot orthopedist that I originally saw had actually REFUSED to order one. His reason: Not indicated, although there was pain, swelling, affecting my gait and already compromised balance issues. I became angry, and in a controlled voice (trust me, it took a great deal of self-control!) I demanded he do SOMETHING. He acquiesced to a nerve conduction study and wrote the script, although he did so with a cynical "I doubt that it will reveal anything." He did not call with the results, so I made an appointment, at which time he told me I should just get on with my life and stop looking at what I considered to be "impediments" to my resuming activities that I had previously enjoyed. I dropped that orthopedist for his refusal to recognize my pain and failure to do anything nearly 6 months after the serious injuries and the increasingly compromised ankle/foot/leg...
I sought doctors from a different medical group, and the new neurologist (Dr. S) performed a thorough exam of the entire appendage, and also verified that I had nerve damage that radiated up the leg. He also affirmed that the discoloration of skin bilaterally and on top of ankle was an indicato of CRPS, along with the swelling (still there, 1 yr after the injury). I had received a consult with a foot orthopedist in private practice, and he also performed extensive examination and injected both sides of ankle. That did not help, just hurt really intensely. So after all of that, Dr. S. made the diagnosis of CRPS Causalgia (which occurs after a distinct nerve injury). I had had PT (ordered by my primary, shortly after the fall) and it had not helped. To cut to the chase: there's more to my CRPS journey, but I've addressed your question. You can find more info on the Mayo Clinic site ("Complex regional pain syndrome"), which explains symptoms/causes as well as diagnosis/treatment. There are other sites online that are reputable. I use ONLY sites from recognized and respected medical universities, hospitals, and organizations. I also like medical journals, including those from the UK and Australia. Very informative, and helped me to better understand the "why" of the physical and emotional-psychological components of this disorder.
Hope this helps. CRPS is not an easy road by any means. It will be 3 years come this June that I incurred the injuries, and I'm still dealing with aftermath to my left leg (yes, the entire leg including the knee and thigh). And my pain management doctor sees evidence that the CRPS has "mirrored" to the right leg as well. Yeah, it can get "funner and funner."

Best of luck to you. Feel free to reach out if you have anything you'd like to share, or any questions. 🌺