Son's rights in child support

I have a 3-year-old son who is currently being diagnosed with a disease that requires immediate medical attention and enough funding to avoid complication in his heart. Prior to this situation, I have asked his father months ago of his paternal obligation and financial support to our son but he has intentionally ignored us up to this date because he has a new family but they know of my sons' existence.

I am very much desperate considering that time is very important and I don't have enough money to support the medical needs of my son. How can I oblige the father who is currently working in a big company in Dubai and does nothing on this matter?