It's not unusual to test positive for small fibre neuropathy with CRPS. This is something that has been looked at in research and been found to be a feature of many patients clinical presentation. Some articles and doctors describe CRPS as a small fibre neuropathy condition. Most CRPS patients aren't tested for it because it would add nothing to the diagnosis - if you have CRPS there's nothing they can do about the neuropathy and doing the skin punches themselves are likely to be very painful, possibly inducing a spread or a worsening of the existing CRPS.

How long has this deterioration been going on for?

The kind of deterioration you are describing with your exercise could simply be the progression of the kind of dystonia that can 'normally' be found in CRPS. I'm not saying it is, just that it can be. Pool exercise isn't weight bearing and if you are very inactive the rest of the time it may not be sufficient to maintain normal muscle mass. I gradually lost all my ability to kick in the pool, to walk and to move my legs on a stationary bike. Ive never recovered that ability. The deterioration was initially very rapid and then progressed more slowly over about 2 years. i have significant muscle atrophy. I had an initial movement disorder spread pattern that was typical of both CRPS dystonia spread and SPS. As I said, all of the things you are experiencing 'could' be described by high levels of general inactivity.

As fMichael said GAD65 levels can be elevated in other conditions. Diabetes is one. In the SPS cases where it is found to be elevated its typically at very high levels, its elevated at much lower levels for diabetes. Not that it's found to be elevated in everyone with SPS.

I seriously recommend you do as much research as you can of your own into SPS and CRPS related dystonia to try and match your own experience with what is described for both these conditions. Look at as many sources as you can and I still think you need to take a hard look at your medical team to be sure that they really know what they are doing - for something like a serious presentation of CRPS dystonia and for SPS diagnosis you really would want to seek out neurologists who have some experience of These conditions and get a second opinion. I had to go abroad to do that and went to a global leader in this stuff. It was worth it.