Low blood pressure + extreme heat is the cause for me. I also have cptsd and adhd so I dissociate too. If you struggle drinking water, try eating high water content fruits and veggies. I can tolerate watermelon and cucumber most easily as I deal with GI issues as well. I found a list for you: Melons such as watermelon, honeydew or cantaloupe Strawberries Pineapple Peaches (I also like plums too) Oranges Bell peppers Broccoli Celery Cucumbers Lettuce Zucchini I hope this helps!

Oh! And you can help maximize the effect of the water by adding an ORS (oral rehydration solution) like liquid iv, drip drop, banana bag. Caffeine dehydrates so stay away from that as much as you can. Gatorade and powerade really don't help bc the sugar content, also dehydrating, is too high. You can cut it half with water to make it better hydration-wise if that's all you have access to.

Brain fog/ fatigue

Water and salt are the saviors. Salt Stick Vitassium salt caps help me get my recommended 5-7g of salt a day in. For water, I get a 24 ounce bottle, fill it up with cold water, and keep it on me at all times. I've found that if I drink around 6 a day with the salt, my brain fog goes away.