lol. They make formulations you can buy but I make my own. A cup of ground mustard seed, which I buy fairly cheap online, and a few tablespoons of baking soda, plus some essentials oils mainly to cut through the mustard smell.

Pour that in a warm bath and soak for 20 mins. Then get out and wrap yourself in a towel and continue sweating for 15 mins or so.

Maybe chuck in some chilli next time too?

Sounds like you're making human soup? :)