My Father Is 90 Years Of Age, He Has Had

My father is 90 years of age, he has had some issues with his kidneys, he was treated for a serious UTI back in November at the hospital. In the last few weeks, he was unable to "make water" or urinate. We took him for a checkup at the VA this past week and did a couple of tests and was unable to give them an urine sample the at the visit, so I took him back the next day and we had to time it closely but we gave him a beer to drink which enabled him to give a specimen. He complains with "burning" in his right side, I feel sure it must be connected with the kidneys, but we have not received any results from two tests and his next appt is not until Feb 10th. The burning sensation is that something that should be checked? I feel that we should take him to see another doctor - maybe Urgent Care? Do not know if this could be signs of kidney failure? Could you please advise me on best care for him?