Welcome to the site, I am glad that you found us. I hope you will find helpful information that can help you and your medical team unravel what is going on with your body. It sounds like you have had a rough time, sorry to hear that.
It could be that you have multiple things going on. I have communicated with many ppl who have the hot version of crps, I dont think it is less common.
You are correct about this disease having the ability to show up uniquely in individuals. And for the most part it does begin with a limb. You mentioned that you were having problems with your arm/shoulder and that certainly could have been a catalyst.
The intolerance to clothing on your body certainly makes a strong suggestion for crps. I have a hard time sitting on hard surfaces too. I dont recall you mentioning any unexplained swelling. Have you ever looked at the Budapest criteria? I guess it is used in the ruling in/out process for diagnosing crps.
Please come back and let us know how you are dojng.
Barb