For Me.....
As was mentioned, if ALL else is ruled out thru tests etc then it is RSD, a SUDDEN issue could also be the reason why it is. I was sitting here one day after being an active long distance walker, I also walked a LOT at work. Never smoked or drank in excess, my diet was considered well balanced, cholesterol was excellent ALL that has been taken into consideration. My heart started being odd, I was feeling ILL so went to chemist to get a BP test, they found my pulse rate was irregular and was racing...I was taken to hospital immediately. I worse a cardio thingy in a harness and it showed 2 forms of issues. So i went and had a stress test with cardiologist. It was just said it WAS, my gall bladder had no issues before no stones etc. I collapsed at home a fancy test showed it was only working at 77% reduction in a week it had basically stopped and I had liver and kidney issues starting so out it came. I have had that many tests and scans and MRI's I guess that is why they came up with this.....but i CAN tell u something, it is frustrating because anything new happens and i dont know if another RSD or if an actual problem...do I stay at home or urgently go to the hospital. I am happy to talk with you in depth if u wish about specific regions you might be having issues with and let you know what it is I would be asking. Hope this helps...PS,, like RSD in brain or body, there is NO use stressing about it, the docs will get to the bottom of it and they will sort it out. Afterall, that is WHY we pay THEM