What triggered POTS and other issues?

Hello,

It’s a strange situation, but maybe someone has some insights:

On July 4, my gastroenterologist conducted a routine gastro check-up. He recommended doing an endoscopy with a biopsy without anesthesia, and I agreed. This was probably my 5th or 6th endoscopy in the past 10 years, but I had never had a biopsy taken before. It was due to gastritis. After the procedure, I noticed something wasn’t right—my stomach started cramping intensely. A few days later, I began experiencing heart palpitations. This marked the onset of POTS symptoms (I’ve since done poor man’s tilt table tests, and they’re always positive).

A few weeks later, I completely lost my appetite, experienced nausea, and started having epigastric pain—this pain felt completely different from gastritis. These issues have persisted ever since. Starting in October, I also developed constant headaches. All my tests have come back normal, except for an ANA of 1:100 with homogeneous fluorescence. However, all other ENA, C3, C4, and anti-dsDNA tests are within normal ranges or negative.

I can’t figure out how or why POTS and gastroparesis symptoms developed. I managed to see an excellent cardiologist, who referred me for a tilt table test. I had to postpone it as I started feeling unwell, but for now, everything points strongly toward POTS. However, I have this gut feeling that it’s a secondary type, and I can’t understand what triggered it—all my symptoms began after the procedure. I even considered lupus because I have something resembling a butterfly-shaped rash. But doctors said it’s dermatitis, which I’ve had for 6-7 years without any other symptoms.

Right now, it feels like my entire system started shutting down after the endoscopy with a biopsy.

I’m not asking for medical advice, but does anyone have any insights?