What causes pain in right flanks and low back pain?

Many: A kidney stone or a kidney infection can cause low back pain and flank pain. It largely depends on the other symptoms you're having. The pain with kidneys would be near the bottom of the ribcage. Difficult to say for sure without examining you. Please see your pcp if the pain continues.

Various : Various kidney problems including infection, stones; vascular problems -- like abdominal aortic aneurysm, ; muscle sprain; shingles and herpes zoster break-out; thoracic spine or lumbar spine arthritis, pinched nerve in lower thoracic spine, there are many such causes -- including more urgent issues. See your doctor, for an examination to figure out which of these could be causing your symptoms.

Sciatica: This pain pattern is correlate with pelvic girdle dysfunction, which medical literature reports to be the pain generator in up to 30% of people with chronic low back pain. For more information about this topic see my chronic pain board at quora.Com.

Evaluate Low Back: If you are not improving have your doctor order a lumbar spine mri. Many times a herniated disc in the back can cause leg pain especially if you have not improved with the medications and physical therapy. If it is a herniated disc you may need evaluation from a spine specialist to determine what other options might be needed (injections, surgery, etc) to help reduce pain.