What Causes Chronic Pain On Right Side Of Head?

My Friend is having pain on the right side of her head which has lasted about 2 months. She has gone to the hospital and doctors office many times for it. She has had ct scans and mri scans and all have shown normal. She has been taking lots of ib profen and no change in pain. I am also her boss and she has missed lots of work because of it. any suggestions on what she should do?