Location: WA state paid sick leave

Hello I’m in Washington State and I’m wondering about paid sick time laws. My employer is denying me paid sick time saying I have “used too much” which by there standards is 5 8 hour days total per year. I’ve saved up more than this and none of this sick time I’ve taken has been more than one day in a row except for this last one which was two. I can’t find anything in the RCW about employers being able to set use limits. Does anyone know or have a link to the relevant RCW? Location: WA