Deductions & credits

I am the custodial parent. My ex is allowed to claim one of two children every other year. 2019 is the first year. When he claims that child am I allowed to claim what I paid for her childcare? Jan-oct 2019 I was paid through child support for a estimated portion of childcare cost. My understanding is there was a deduction in the form 14 for the credit. Then we split costs Oct-Dec 2019. So I am confused to what I am allowed to claim.