Infection Persistant drainage from ear

Hi everyone. I'm hoping to get some advice here. My piggy, Charlie Brown, has had pus draining from his ear for almost two weeks. He had no signs of illness, and had actually been gaining weight (from being down after a problem with inflammation in his eye and bullying by his then cage mate), until I picked him up for his daily eye drops and he had crust and pus draining from his ear. I took him to the vet immediately, and he was placed on a sulfa antibiotic orally, along with Baytril drops for his ear. The culture came back as Pseudomonas, which was resistant to the sulfa, so the vet started him on Ciprofloxacin orally. After 4 doses he completely lost his appetite, so we did syringe feeding with Critical Care and water by syringe all this past weekend. He's now eating on his own, but the pus just keeps pouring out of his ear. At the vet's advice, we discontinued the Cipro, but the ear drops are still being administered I clean it out twice or three times daily, prior to administering the drops. He is one ticked off little dude, as I'm sure it hurts like crazy and he hates getting the cleaning and drops put in.

Does anyone have experience with how long this might go on, and if he should also be on a pain reliever? My vet has been excellent (and specializes in exotics), but is on vacation right now. I've been contacting him at home, because he is so wonderful he gave me his home number and said not to bother calling the clinic until he gets back, but I'd like to see if there's other info out there from the cavy community. He's also quite expensive, and this has already set me back over $400, so if I get a little advice here, I'd really appreciate it! Thanks!