I'm a lot older than most of you and have been diagnosed with some pretty serious matters. I firmly believe that one autoimmune disease can lead to another.
Perhaps on their own they would lead to PEM, who knows? But in my mind, what difference does it make? If you have other serious illnesses that follow, you can't even begin to separate one from the other. All exist and have to be treated in their own way.
Not every doctor is capable of making diagnoses, that's why it takes an average of many years before we find an answer to our problems. Keep looking, take a break (as I know it gets tiresome) and then start again. In order to be properly treated, whether naturally or with meds, we need that proper diagnosis. If not, we could be harming ourselves.
Lupus is one of autoimmune diseases that killed people in my nursing days. Today, thanks to modern medicines, a lot of these people are not only living but living normal lives. Things do move along, but it does take time.
@heapsreal posted a video of an interview given by Venus Williams. Do watch it as it contains not just info about her specific diagnosis, Sjogren's Syndrome, but acknowledges that other autoimmune illnesses can occur. She's quite right....and the older you are, the more that's true. Not in everyone, of course, so please bear that in mind. It takes a lot of trial and error until we find out the answer for one of our symptoms let alone those who have a number of autoimmune illnesses. I do wish better health for all of you. Yours, Lenora.
