That cat may have been abandoned. If you don't find her owner soon, you might consider taking her to your local shelter. At least there she would be cared for and fed.
Thank you so much for that. She didnt have symptoms of tonsillitis to begin with. It was picked up over a general check up. There is a new cat in the neighbourhood that sneaks through our back door to eat her food, and our vet believes she may have picked up tonsillitis from that cat. We have sanitized her bowls and eating mat and have kept her inside for 2 days.
I let her out for 10 minutes today, and she's calmed down now and is back inside. We're keeping an eye on her outside just in case the other cat comes back. In that case, we'll just shake her packet of treats to get her back in and lock our cat back inside. We are having problems tracking the owners of the other cat to let them know that their cat probably needs to see a vet. Our cat's food is no longer in the kitchen (which is the back entry to our house). We've moved it to our spare bedroom, so there is no chance of the other cat getting to it.
Anyway, thats the steps we're taking at the moment. Our cat seems fine. Eating normally etc, but we're still worried as she is still on antibiotics and we dont know who owns the other cat that always comes over. The other cat is definitely owned because she has a collar. There is no name etc, just a standard bell flea collar.
Tonsillitis is an inflamation usually caused by a more general viral or bacterial infection, hence the antibiotics. Letting her out while she is infectious is a risk to other cats she may come into contact with. Letting her out while her immune system is compromised by having an infection is a risk to her. Having said that, if her symptoms have started to improve the risk may be minimal, but I wouldn't let her out for too long and if possible keep an eye on her to keep her from other cats and out of anything that could further tax her immune system.