First off, you don't need a prescription to apply diluted Betadine. It's a mild antiseptic.
Having said that, I would wait and see how it progresses over the weekend. Snakes can get contusions just like any other animal. If it's swelling from bruising, give it time to go down.
Don't mess with the animal, don't pry it's mouth open. Give it a couple days to see if it's something that will resolve on its own.