What is the best treatment for scorpion sting?

Symptomatic. Most scorpions in my area are non-venomous. So i would check with your doctor regarding how dangerous scorpions are in your area. But most can be managed with a cool pack and benadryl (diphenhydramine).
Depends. This depends on the type of scorpion that caused the sting and the severity or grade of the envenomation. But generally, most us scorpions cause a sting like a bee. So unless you have an allergic reaction or if the species is an "az bark scorpion (centruroides exilicauda), the treatment would likely be simple cleaning of the wound and making sure that your tetnus status is up to date.
Scorpion. Wash area of the scorpion sting with water ; soap. Apply cold compresses. Avoid eating/drinking anything initially. Remain calm. Pain can be tx’ed with nsaid’s. There are very few scorpion sting deaths in the us. If child is stung- seek med tx. For ^heart rate, ^ respiratory rate, weakness, ^ blood pressure or muscle twitching seek medical care. If out of the us or generalized sxs seek med tx.