When a chin has a bladder/urinary tract infection or stones it can lead to an extremely bad problem with him not being able to empty his bladder. It hurts and it causes the bladder to swell to the point that permanent damage can be done. The tissues are inflamed and it makes it hard to urinate. This could be something that a vet could flush out and give antibiotics to make it go away.
A chinchilla with a bad urinary tract infection or stones can die from it, and die fairly quickly. Since your chinchilla is active and moving around, it is a great time to take him in since there's a much better chance of him getting better. If you wait, he will get worse and you may end up having to have him euthanized.
A vet really is necessary because there are no home remedies to solve the problem. I know that money problems can make it difficult, but you really should take him in as soon as possible. Around here I frequently have issues with running low on cash and worrying about taking in chins that need to see my vet. I always find a way.
The last three years have been absolutely excruciating because money is so tight and more and more people surrender chins that are in great need of vet care. I always find a way, and I know that you can, too.
Where are you located? Maybe we can find a vet for you to take him to right away.