My dad (being a country old timer) uses a lot of self made remedies. One of those is Yellow Root Tea. He uses this tea to treat stomach issues like diarrehea, vomitting, and upset stomach. This is a very nasty tasting concoction but it has worked for me since I was young. All of us kids call Dad whenever we have a stomach virus and to the kitchen he goes. Dad digs his own yellow root, so I am not sure where you can obtain this...
Dad dries the yellow root and cleans it and keeps it in a dark place until needed for later use. To make the tea he takes a 3 to 5 inch piece of the root and puts in a saucepan with water. He then boils the root for about 30 minutes. He removes the root and you drink the tea left over in the pan.
I let mine cool and drink it that way, but no matter hot or cold, it is very bitter and nasty, lol.