Charlie's Sick :(

My cat best friend Charlie is sick. Ive been traveling for work and came home to find Charlie has not been eating and skinny (which Charlie loves food and is the ultimate fatcat). I took him to the vet and was told that Charlie is showing signs of yellowing on his face, ears and gums and his weight loss could be the result of something wrong with his liver. The vet also found a lump in his stomach, which could also be affecting his appetite (could be anything, something weird he ate, cancer, who knows). 
To start to find out what is wrong with Charlie, he needs blood tests and xrays, which comes out to at least $400 but this is just the first step of making Charlie healthy again. We have no idea if it will be an easy fix or the start of something else...
I just got back into town and am flat broke.  The last company I freelanced for owes me a ton of money, and has failed to pay. I don't have family that can help cover this and I just need Charlie to be his happy stuffed animal cuddly fat self. Any donation would be appreicated. I really hate having to ask for help, but I unfortunately have no other options. My other cat Milo was recently sick as well and I had to exhaust my money on getting him better and purchasing his perscription cat food.