Have you had much work up on your possible neck injury? It may be worthwhile to see a spine specialist or a Physical Medicine and Rehabilitation doctor. Different disciplines often have very divergent approaches to the same problem.

It is always good to get information on all your options. I can understand not wanting to go to infusions right away. However, it looks like you have tried a lot of medication options already. If you have had adequate work up to identify another cause of your symptoms and are having so little relief or improvement then LDN or ketamine would seem like a natural progression. Dr. Pradeep Chopra recommends LDN highly and has a two case study published with pretty phenomenal results. One with significant ankle/foot curling. Stanford is currently doing a study on LDN for CRPS. The ketamine can be started low and titrated to see if you tolerate it. I react poorly to darn near everything and surprised myself doing fine on the ketamine.

One thing to keep in mind about infusions... You are not signing up for ongoing side effects like an oral medication. Ketamine washes out of the system very quickly and you are done with it. This is part of why it is so safe and used frequently for anesthesia even for children in ER settings for fracture reduction, etc. Lidocaine has greater cardiac side effects from what I recall. The published evidence for ketamine is positive for CRPS and at low doses the side effect profile negligible. You can check out studies on Pubmed. I have to say that it sounds like you have found a pretty progressive doctor if they are already offering this to you. Perhaps they have other tricks up their sleeve as well.

You can also try a short round of steroids of you haven't already. They are considered a front line treatment to reduce inflammation. A ten day course of 10mg 3x daily is the standard for acute CRPS.

No matter what you choose be sure to give it adequate time unless side effects are intolerable. LDN can take some months to work and ketamine gives a gradual cumulative improvement.

Do you have access to a pool? Many of us have had substantial benefit from swimming or even just swishing around with a buoyancy belt.