I've had back pain for about a year now and it doesn't seem to go away. It is on the right side/flank in the center of my back at the far end of my bottom rib, directly on top of my right kidney. If I'm standing with my arms loosely at my sides, it would be basically touching my right elbow, or a couple inches away. I've seen several doctors over the last year including a urologist and I've had an MRI, CT, and ultrasound, and they all come up negative for anything. My kidney is fine, no cancer, no kidney stones, bloodwork is good; I'm young and in great shape overall so I'm going to assume it is a garden variety muscle strain. It feels like a knotted/pulled muscle in one tiny spot like someone is pinching me real hard there, or just digging their knuckles into my back. Massaging it feels really good but doesn't solve anything. Anti-inflammatory drugs and other painkillers do nothing. I took a month off from tennis and it still didn't go away. Off the tennis court I don't do too much exercise or cross training, but I do run, bike, and swim occasionally and I do situps, pushups, planking, and other core exercises for strengthening. I play mostly on hard courts using a Dunlop 200 4d racket. Someone recently suggested this could be the culprit. The dunlop 200 is a heavy racket, 18x20, with very low power and small sweet spot. http://www.tennis-warehouse.com/descpage-D4D2.html I have to put my whole body into it to generate pace. Since I'm young and healthy (25, 6', 190lb in good shape) this has never been an issue for me, but if it is the cause of my pain I'll switch rackets. Has anyone else experienced this kind of pain in the right flank area? Again it is at the end of my bottom right rib right by my kidney in that area and I have pretty much ruled out the big stuff - kidney problems, cancer, sars, lupus, aids, etc. Thank you! Sorry for the lengthy post.