Jack needs your help

I adopted Jack at the age of 12 about 4 years ago. He was found emaciated as a stray in Georgia, but thanks to two different rescues who saw how special he is, his life was spared. Since I've had him, his fur all grew back, he gained 20 pounds, and has been overall healthy. Until recently, when the other day I found a growth on his gums. His teeth are bad, but the vet didn't want to do anything due to his age, but this growth is another story. At this point, we need to do something about it. It doesn't seem to bother him, but it is growing, and it's only a matter of time before it causes him issues. This boy is truly special and my best friend. I need to have him taken care of and unfortunately, money is tight. My hours at work are cut until October.