Angry bum

Guys shame so my dog has recurring bum problem. Her anus gets really red and "angry" as the vet says, it gets a bit oozy and smelly from time to time. She's an old Maltese but I've never come across this problem with any other dog we've had. We have a cream from the vet we use to treat it when she gets a flare up, we use the cream for a couple of days and then she's fine for a few weeks again but it just seems like a strange and annoying situation.

Does anyone else's dog have this issue? The vet didn't say anything about whether it's food related or allergy related or anything so I don't know how to keep it from being a recurring problem.

*thanks for the answrss. It's or her anal glands. She's at the parlour often and when she was at the vet, they were clear.