On the ice water immersion it was noted in the Lewis and Clark Journals that shortly after arriving in what is now Washington state they had a member of the party get extremely sick and the couldn't move him. They waited around and figured he was going to die. The local Indians gave their 2 cents and it was followed: stuck the guy in a sweat lodge till he was incapacitated and then took him out an threw him in the cold river. After about 4 times of this the guy was much better. I think he just got damn tired of that torture and just said he felt better
It has been some years since I read the Journals but I do recall that story from them.
Blackberry brandy, commonly used in my part of the country for snow snake medicine, kill jug drink of choice, and a little shot of warmth on a below zero day. For those that don't know what a kill jug is, it is a bottle of spirits that are carried along on a hunt and when critter has been taken the bottle is passed around, usually until empty. Don't ask me about snow snakes, I've never seen one.....
The last time I was really bad sick with fever and all the extras I laid around and watched tv and didn't feel like eating much. After couple of days of this I was watching a movie one night and decided I really wanted something to eat. Looked in the fridge and freezer and my eye stopped on the ice cream carton. I ate the whole half gallon in one sitting....nocked the hell out of my fever and I felt much better the next day. That was 8 years ago and haven't really been sick since so I don't know if that remedy would repeat itself.