What causes pain in a point midway between navel and right hip bone?

Many possibilities. You could be describing a hernia, appendicitis, ovulatory, tubal or other gynecologic problems, kidney stones, hernia, bowel problems and many other. It would depend on when it started, the progress of the pain, any fever, nausea, vomiting, abdominal distention and many other factors. I believe you should see a doctor asap for evaluation and treatment.