Kitty needs help :(

My cat needs some help. Lately I have noticed he is producing small bumps in his fur mostly near his ears. They almost look like bites and he has been scratching them like crazy. He has also been getting small asthma attacks. I brought him to the vet and they wanted to test him for cancer as he is getting older and take xrays of his belly as they are not sure why he is getting these attacks and it may be internal.  Leaving the vet cost me 400 and to do all these tests apparently are roughly 2500. How is this even affordable? I live my cat to death I have had him since he was 6 months old. He's about 10 now. He sticks to me like glue...he behaves so well. He is truly an amazing animal that needs some help.