Does child support go up if your child needs special medical care?

My ex has been paying child support regularly but now I might need an increase. Our son has been diagnosed with cancer and will need special medical treatment for at least the next 6 months. I’m discovering that many of his medical bills are not covered by insurance and I’m having to pay them out of pocket. I’ve asked my son’s father to contribute but he says he can’t afford to pay more than he’s been paying and that we should qualify for some financial assistance from the hospital based on our incomes. Applying for grants from the hospital takes time and I need to pay these bills now. Can I ask for a child support increase to have my ex pay his share of our son’s new medical bills?