My cat has some large clumps of matted fur, never been an issue before, she's a short hair, but had a month of being really poorly to the point the vet thought she was at the end of her life, she is an older cat at 13, but then made a rather miraculous recovery. We're wondering if it's because she wasn't grooming herself when she was poorly. I've tried to comb it, but she's not particularly keen and it will take some work, Any tips for helping get the Matt's out?