What Causes Dizziness, Headache And Loss Of Vision?

My nineteen year old daughter has been sick for about nine months with the following sympoms...dizziness, lightheaded, shakiness, headaches at the front and back of her head, loss of vision, loss of hearing at times. She has been seen by a cardiologist, endocrinologist and neurologist. Tests all come back fine but she is getting worse. She is unable to do any real physical activity at this time. Not sure how to help her.