Suggest Medication For Post Viral Syndrome

My daughter has been sick for 2 months (beginning just as she was getting over a cold), 1 month ago she was diagnosed with Post Viral Syndrome, after having many tests done that all came back fine. At first she had diarrhea, but that improved after about 1 month - she is taking probiotics most days now. She is still very tired, with extremely low energy, and often has a headache, and occasionally lightheadedness. Her appetite isn t that good and she often finds it hard to eat very much. She says she is hungry, but then nothing much sounds very good - her stomach also hurts at times. She has been to our family doctor, and to the Gastroenterologist (he did a endoscopy & colonoscopy, which were fine) - they agree with the diagnosis, but don t have any suggestions on things to help her feel better or get over this any faster. Do you have any thoughts or ideas on this.