i experience the same thing. Not sure why this happens.

This used to happen to me. I believe it was caused by the thyroid being out of whack, as it stopped happening when my thyroid improved. The thyroid is the temperature regulator of the body, and when it is slow to respond, the body will become stressed as it works to regulate temperature. Obviously any stress must be compensated through the adrenals so if they are weak the symptoms you described would most likely be exaggerated.When I had thyroid issues, I was also sensitive to extreme changes in weather (cold or hot).

Sodium loss and/or the rarity of an actual detox reaction would only happen if you were sweating profusely in the shower. Too many times people think they are having detox reactions when in reality it is the body saying that there's something wrong.

If I were you I would avoid extreme changes in temperature, and stick to warm showers until you stabilize more. As the adrenals heal the thyroid will follow suit.

I get this too - one time i threw up after having a bath.

I have to have warmish showers and baths now, then lay down for a while after to 'come back'.
I agree with Faith - it's the thyroid and adrenal state that causes this mainly.
With hypothyroid one tends to have lower body temp so bathing raises it and it has the effects you mention.
Also i think blood pressure is involved too - is your blood pressure low?
Mine is and i find i'm especially dizzy and trembly after bathing - my BPM will be racing with my BP extra low after a bath.

It might be worth monitoring your BP.

Maybe vasodilation?...
Just an idea
When BP is already low it would drop even lower due to heat and humidity
I also feel extremely fatigued and nauseous

I have this too. Thank you and responders for posting, it is one of the weirder symtoms of our illness. I stopped arguing with my body and I think so should you. At this moment hot showers do not become your body and you'd be doing it a favour by not pushing it.
(I mean this to be in a friendly tone. English is not my first language so if the tone is not friendly please imagine my beaming face and warm handshake)

I agree it is the thyroid (or the nervous system) not being able to alter homeostasis to the new, hot environment. At first I enjoy it but in 5 or 10 minutes I get drowsy. After toweling off I wish I could lay down (which I often did)

Ever since my thyroid got better (through eating high fat diet, Homo Optimum, Kwasniewski and vitD) I'm able to better withstand showers. Still I only take one ever other day or less (told you I stopped arguing with my body) and make sure I have eaten sufficiently but nothing taxing before I do. I also take salted water with me to the bathroom, to sip before and right after.

Since I fortify my adrenals ( supplementing hydrocortisone) my days are more relaxed, physically. I feel my body is more at ease. It gets better at taking showers now. Which proves to me that it has to do with the adrenals and the regulatory systems of the body. Not with detox. I have been toxinfree for years and not able to shower without an hour rest afterwards during that time.