What could be reasons for chronic R kidney pain? Ruled out stones but I have a HX of stones and infection. It's worse after OTC meds & dark beverages

Maybe not kidney. I assume you are referring to right sided back pain. If stones ruled out by plain X-ray then it may still be kidney pain due to UPJ obstruction,then get ultrasound and possibly CT with contrast. If a renal cause is definitely ruled out then it is possibly musculoskeletal.Talk it over with you doctor.Best of luck.