Headaches, Muscles Aches, Stomach Problems After Anabolic Steroid Withdrawal

My son is 16 years old. He is an athlete who is in good health. Last December he began treatment from a physical therapist for patellar tendonitis. He was treated with steroids for about 3 months. He completed his treatment about 6 weeks ago. During the course of his treatment he gained about 20-25 pounds. He is normally very lean and doesn t gain weight easily. The therapist said that was partly due to steroids and part a growth spurt. We also noticed a much fuller face . Since stopping treatment he has often complained of headaches, muscles aches, stomach problems and an inability to handle stress. In the last 2 weeks he has begun having fits of rage. He has had mild temper issues in the past but nothing compared to recent events. Could all this be withdrawal and if so what should he be tested for and how should he be treated?