子女不履行贍養義務時,無勞動能力的或生活困難的父母,有要求子女付給贍養費的權利
the fee is based on the local living cost. Based on your statement, he has his own income.So, for you, you have not the obligation to pay him right now if the income is enough. However, if the medical cost a lot, you may be judged by court to pay a certain medical cost. One thing is that he must show the reasonable recipt. One more, like others said, China court will not have the way to force you to perform it, but, being a daught, do something is moral requirement.