t mention if you experience any changes in heart rate associated with the
heat but certainly the things you stated seem to indicate an autonomic issue. Cleveland
clinic,
mayo clinic and Vanderbilt all do autonomic testing, I can't recommend any over the other as I haven't been yet, but I was diagnosed with dysautonomia by an electrophysiologist thru a tilt table test. My primary issue was an inappropriate heart rate that was very exasperated by heat.