There are people here with medical knowledge. And in my experience, doctors are often more focused on fixing a problem than understanding it.
Anyway, I, too, am puzzled by nausea. Is there any chance there’s a toxin in your water supply, or activated by steam in your bathroom, that is causing the problem? An organic solvent in the water, or mold in the grout or something?
I read lots of medical sites, too, but I like to hear individual people’s individual experiences. Plus, you can have a dialogue with people on a message board, which you can’t with the Mayo Clinic site.
My medical opinion is that it’s vasovagal, triggered by standing too long, along with being showered with warm enough water to dilate the capillaries, both of which can cause it separately. Combine the two triggers together and the odds are even higher of it striking. Nausea is a common symptom, along with light-headedness. It can progress to fainting. It’s relieved by lying down.
It can also occur when one’s balance sense is off, as can happen while flying or on a boat.
See? That’s why asking this stuff on a message board is mostly pointless. Maybe you get a doctor’s opinion, but more likely you’ll get a bunch of Dr Google speculation that ain’t worth a crap. This is why medical practices have advice nurses.
You’ve made your opinion of opinions clear at this point. If you wish to continue that line of discussion, please take it to a more appropriate thread. Don’t return to this one.
Vasovagal syncope can also include symptoms like tunnel vision. Many of the other symptoms are things you might not notice in a shower such as sweating or feeling warm. If you feel symptoms starting you may be able to stop the progress by laying down. Elevating your feet may help as well.