I don't think there is any other way to get those antibiotics but I'm not an expert.

I can feel you pain because we went through the same thing with Jazz when we adopted her. She had a URI (cold), ringworm, tapeworms and earmites. It took about 6 weeks to get her healthy and around $350 in vet bills and meds. My vet prescribed a special medication for the ringworm that had to be mixed by a pharmacist and the only one who did it was 40 miles away so I had to have them mail it to me twice at $45 a pop. On top of all that Ripley caught her URI which triggered an underlying blood infection that almost killed him and we ended up spending almost $1000 on him.

It just comes with the territory of being pet owners.

Sorry I can't be of any help.