Charlie's Medical Bills

I've had Charlie since he was born, currently he is six years old. I've been taking good care of him and have fed him only strictly his diet food that was assigned to him. However, it seems the urinary stones have come back as he is showing multiple signs of discomfort. He's a very playful and energetic dog and we spend a lot of time together. 12 months ago he caught bladder stones again. They had to be removed through surgery again. Currently, he is showing signs of oversleeping, loss of appetite and straining/little urination. It is unknown right now what he needs but I am being cautious this time. I fear that I wait too long once again and I will not be as lucky this time. Right now I'm trying everything I can to get the money for the medical bills. I'm not sure how much time we have until he needs surgery and anything given would be greatly appreciated.