My cat Dax has days to live without surgery

My cat Dax has a large amount of bloating due to access fluids building up in his body, he has pain pooping and urinating and has only had diarrhea for the past month and likely has 3 days left without surgery. we don't even know what is causing this and to find out and treat him it can cost over 5000$ and we simply do not have the money. I am spending everything i have and that totals up to something like 1200 and since quarantine i am the only one is my family who has working and its only part time at a pet store.

We have had Dax in our family or 13 years and his mother 16, With a cats life expectancy averaging out at 16-18 with 20 being very possible i am not yet ready to let him go and don't know how life will look with out him