My Son Suffered A Concussion Almost 3 Months Ago. He

My son suffered a concussion almost 3 months ago. He refuses to go out to any appointments . we are extremely concerned and have an appointment with a neurologist for him tomorrow. He's 17 and we may be forced to call in paramedics or police enforcement, since he may be endangering his own health. We've been extremely patient, as to not traumatize him, but at this point given his extremely oppositional behavior, we must insist on ruling out a subdural hematoma, or anything else that can medically explain his behavior. What do you suggest in terms of getting him to comply or using force, if need be?