Don't mean to scare you, but... (And I'm sure it's not this because Honda could still walk just limped a lot...)

We thought she had arthritis in her back leg and so the vet put her under for a dental and took a xray at the same time of her back leg. She ended up having osteosarcoma, which I believe is because of injection site cancer. It's the same side my vet always put her injections on. Just something to look for if you end up exhausting all your other options.