Bald patch on cat

[Cybertron]

Our 8 year old girl has a sudden bald patch on her back near her tail. There is a new aggressive cat in the neighbourhood. Is this from a fight? Or is it a skin problem? Any ideas?

Fleas possibly and the cat has been scratching?

My cat was allergic to grain so ended up with a rash on his skin and bald patches where he scratched. All sorted with a grain free diet.

Looks like a flea allergy.

Also saying fleas. Happened to my cat and I was very confused at first

My cat has just developed this in the last couple of months, interestingly she's exactly the same colours as your girl. She’s had 2 courses of steroids but each time we stop it comes back worse.
No-one, not even the vet, can find any fleas on her, but we are now part way through an intensive treatment as it does look like a flea allergy. Currently we are using steroids, antibiotics, she’s had a spot-on flea treatment, and a spot-on tapeworm treatment.
The steroids will gradually be tapered off from the weekend and we just have to see what happens then, hopefully it will be the end of it.

Looks like a clump has come out after a fight.

One of mine has a flea allergy but for some reason the fleas clustered round his neck so all the bald spots were there, but it could be that too.

Flea allergy.