That has happened to my Bingo and I didn't know what to do but to get his hair cut and now I learned to cut most of his hair and brush him even if he don't like it but now his hair is growing back wavy and since he don't like to get brushed I have no choice but to get his hair touched up every 5-6 month's but he does really good in the bath tub he loves the water...I guess she just needs patience for her Yorkie cause if you don't have that and don't get done what needs to be done your just neglecting the dog from his/her needs