W-4S Sick leave - wants to make me leave feeling sick

Hello! 

so I am super stumped on filing a W-4S for sick leave tax withholding. I have my gross income of 83,907 and I’m filing single. I have a tax of 11,227. I’m stuck on the part about the amount of sick leave payments. I expect to be out for a month, so to me, I get paid every other week meaning 2 payments for my sick leave. However, I feel like withholding close to 6k in taxes seems like it’s too much. My current tax withholding is about $400. Should I just write down my current tax withholding for the form or did I do something wrong with the math? 

thank you!