My significant other just returned from an mri evaluation of his lower back and kidneys. He s been having lower left sided back pain for a few months worse after power walking or standing on his feet. He s also had irregular urination from hardly any to too much, MRI shows spot on liver. All other tests have been negative. They want him to have a cat scan with injected dye. He s 68, thin. eats healthy and exercises. What could this be?