PANDA syndrome was my first thought as well. Have a thorough workup by a rheumatologist, as autoimmune problems can contribute to psychological issues.
Another thought could be an extreme reaction to hormonal imbalance of some sort, such as thyroid issues.
Dr. Rosario Trifiletti specializes in PANDAS/PANS. This is the doctor my friend now consults with for her son. I have sent her this thread link. She is not a freeper, but she is a kindred spirit. Maybe she will chime in...