Past due daycare payment

Hello all, I have a past due balance at my child’s daycare that I could use help with. I spend $900 a month usually split between my ex and I and he had claimed to pay it but did not. I have the $175 but am short the remaining $275. If i don’t pay she will not be allowed back,and this will throw off my work schedule and possibly make me lose my job and I really love my job. This is a lovely place and most importantly I feel safe and comfortable with her going there and I would hate to lose them. If anyone can help me, that would be awesome.