This was practically my brother and me for a couple years. Eventually it got labelled "chronic fatigue" (one of the biggest umbrella terms ever). I have no idea if it's at all the same thing, but I can absolutely attest to fighting the same stigmas.

We went through a couple doctors who were convinced we were faking everything because the standard (and plenty of non-standard) tests didn't show anything they learned in school. We had fights with the school system (eventually switching to homeschooling (which is far from stigma-free itself)). There was plenty of family stress, as you can imagine. It's infuriating and depressing and ludicrously hard to find anyone who's willing to work with you.

At least we have the internet now, so the crazies can find each other. Obviously a double-edged sword, but otherwise things like this never get noticed.