Hello.
Back in the early 90's I had a commune tank with B. Jacksoni's (red thick tails) and Centruroides Gracilis (Florida Bark Scorpions) and have been tagged by both. The stings from both were very painful and I assume that's because they managed to squeeze out a good deal of venom in the stings. It felt like liquid fire inside my hand that spread outward from the sting site. The pain lasted roughly 24 hours with stings from both. Not something I'd really want to feel again.
What I did to help ease the pain a bit was to get a strip of gauze, wet it, and dip one side of it in baking soda. I wrapped the gauze around my finger (baking soda against the skin / sting area) and I let it dry. It did help lessen the pain just a bit... but a bit was well worth it.