Anyone know what this is on my cats back?

We've been putting antifungal cream on it, but it's gotten worse. Help

@Sarah Bogle, welcome to the Catsite
Wound looks rather bad. Better have the vet take a look at it rather than self medicate. Wrong administration of medicine can cause dire results. Bring your cat it quick.

I meant bring your cat in quick. Not it quick.
And thank you jcat for your purraise

I would not put antifungal cream on an open wound. I would call your vet and get her looked at. in the meantime-keep it clean with a warm moist clothe. you can dab some Neosporin on it BUT make sure cat doesn't lick it off-what my vet said-you can apply it to the wound-hold the cat for 10 minutes then wipe off any excess with a dry clothe-that way any medicine gets inside the wound and helps fend off any infection. you don't want It to dry scab over it until the vet looks at it. some vets may want to bandage it and others say air is better-it all depends on the vet.

Do you know how this got here?

Is your cat indoor or in/out?

When did you first see this wound?

Also don't forget to call your vet - maybe they have email? send this picture to them?!

Another vote for the vet quickly.  That looks uncomfortable and the cream might be harming rather than helping.