Suggest Treatment For Pain In Lower Back And Rib Cage

My daughter (50 Yrs old) goes to the gym 5 days a week.. she had a deep muscle message and the next day the pain in her lower back rib cage was unbearable. She sAID IT IS OK UNTIL SHE LAYS DOWN...THEN IT IS TERRIBLE. sHE Had an xray today and nothing showed...however there has to be something wrong...can you help.. No pain until she reclines then it is terrible. Thank You YYYY@YYYY