I've got a fluffy cat and every winter when she's extra fluffy she gets a few issues with a poo in her fur

(yucky). She's just come in and my new super sensitive nose sussed it out and got DH to sort it out though she still smells a bit stinky. Anyone else had this problem? Do I shave her butt? Does the vet deal with this do you think or do I need to find a cat groomer?