Hi if you have a longhaired breed you should be prepared to groom your cat at least a couple times a week.Preferebly every other day,prevention is better than a cure.If you groom daily it will be a pleasant experience,leave it to the stage when they are matted,it will be a painful one.If you take her to the vets they will probably shave her/him,you could contact a groomer and ask advice.Invest in a rake brush for long haired breeds.As far as the bum end goes has he/she got diareah? you could trim the hair around her bum with some rounded ended baby scissors.