Please don't go giving random medications to your snakes. It really irritates me to see people recommend that. The reason why we have so many antibiotic resistant germs out there is people taking medicine they don't need or for the wrong thing. For crying out loud, you wouldn't treat your sick child with dog medication to save a few bucks, so why on earth would you give horse or chicken medication to a snake?
If you can't afford proper care, including vet visits when necessary, don't own the animal!
And believe me, I'm not just spouting pro-vet rhetoric. I lost three beloved animals to different vets who did not know what they were doing, so I don't automatically trust someone just because they are a vet. However, NOTHING replaces a knowledgeable vet for treatment when it's needed. Sure if your snake got a minor cut or scrape, or a stuck eye cap you don't need a vet. But don't mess around with something like an RI. Look for a reliable vet in your area, talk to them and get to know them before you need them, so when something comes up, you know where to go and what to do.
Gale