Is it possible that it could be a muscle spasm? Ask the doctor if that could be the issue. In that case, physical therapy could help.
Did they ultrasound your gallbladder? Gallstones can cause pain in the back or even the shoulder (not always under the right ribs). Does anything specific bring on the pain? Stress, food, lifting, coughing, deep breaths? Do you have any other symptoms? Nausea, shortness of breath at other times, cough, stomach pain?