I have DDD and also had a botched angio that caused even more nerve damage. For the first few years I was told it was all in my head, but I refused to listen to that even though it meant that it was hard to get treatment.
Then one day they did an MRI and a neurologist sent me for back surgery to fix the back problem. That is when the surgeon came in and said there was not enough wrong to do a surgery. She then asked me if I had ever heard of RSD, I had not.
My doctor didnt think it was that, he leaned more towards the PN from the L1 - S5 nerve damage, but sent me to a vascular surgeon. This doctor looked me over and was fairly thorough, when he says you have RSD. Now mind you no one had told him what the back surgeon had said. So it was RSD. This took over 3 years from injury to knowing.
There is no cure, and still some doctors say it is in my head, but at least the knowing is there. So I totally feel for you all without the knowing. You might look into the RSD thing, you never know