The swelling pain on the right side of the back can be caused by the following reasons: First, kidney tumor, when the kidney tumor is serious, there can be swelling pain in the kidney area of one side of the waist, which can be accompanied by urinary symptoms, such as hematuria and proteinuria, and early examination of ultrasound, CT and urine tests of the kidney are needed for diagnosis and early treatment. Secondly, tumor in the lumbar muscle, when there is a tumor growing in the lumbar muscle, there can be swelling and pain in one side of the lumbar area, and the swelling can be palpated during the body check, then ultrasound, CT and MRI of the lumbar muscle should be checked for diagnosis and early treatment. Third, kidney stones or cysts can also have symptoms of swelling and pain in the kidney area, and ultrasound and MRI of the kidney should be examined for diagnosis and early treatment.