I does sound like RI to me too. I also would recommend a vet and a culture. Some vets allow a spread out payment. (my old vet allowed 30% and than 25% a month for three months yup a 105% of the bill 5% for the service) My new one does not at all. It is worth checking.
You have lost a snake to the same issue if that was recently I would seriously look very hard at your husbandry!! How you clean your temps and you ventilation/humidly if it is RI high humidity and low ventilation can often cause repeat RI. In any event a correction in husbandry can save you lots of grief in the long run.