I just read an article about why scorpion venom is so painful - apparently scorpion venom is mildly acidic and the acid facilitates a chemical reaction which causes the pain receptors in the brain to activate more than they would normally for the same dose of the pain causing venoms. The article made me think about your crazy ass @pappa-pepper :) If you are curious to read it here is the link to a summary article - the summary does contain the link to the original scientific research paper as well:
https://phys.org/news/2017-08-scorpion-painful.html