I think you need to be examined for your back also. kindly see an orthopedic surgeon at times pain from back also shows up in the abdominal region. ultrasound of normal rules out kidney or gall bladder
problems. the other possibilities are Flatulent Colic, Colitis- infection of colon, Pyelonephritis
etc depending upon the levels of the right abdomen. You need to take up the following tests:
1. Complete Blood Count
2. Stool Examination- Physical and Chemical
3. Urine Examination- Physical and chemical
you are already taking up.
5. X-Ray Lumbosaccral spine- AP and Lateral.
You can also consult Homoeopathy, it is also quiet effective.
Wish you a speedy recovery to health.