My dog has bloody urine, ive been treating for 4 mo. at vet and no cure... what to do now?

I hope you have better luck with the base vet. If your dog has crystals in his urine he may have a urinary tract infection that will eventually end up in bladder or kidney stones. Do some research on struvite or oxalate stones in dogs. You will have to change his diet so that the pH of his urine is changed. There is no one diet that is good for all dogs so you need to know what you are doing with whatever you decide to feed. Joining K9Kitchen, a yahoo group would probably be a very good place to get help with his diet. Unfortunately, vets aren't usually that schooled in special diets and rely on prescription diets that although they are properly formulated are quite unpalatable for most dogs. I hope things get better for you and your dog.