Sounds like Autonomic Nervous System Dysfunction, more specifically POTS (Dysautonomia International). It's known to be triggered by viruses, infections, trauma, & vaccines. CNN has done scare articles about people getting it from the CCP virus, but any viral infection could trigger it. Compare the symptoms of it with people's complaints of "long-covid", many of those are getting diagnosed with POTS & joining our online support groups. We are now seeing an influx of people joining that are getting diagnosed after the vax.