From my experience with RIs you need to go to the vet....it's only going to get worse on its own. If you don't want to pay for a full visit but can confirm thats what it is, ask if you can purchase the antibiotics on their own. They aren't very expensive and should help you snake recover. Either way I'd seek treatment asap...and I hate to say this, but if you can't afford a vet visit, you can't afford the pet.
Good luck!!