The only way that the occult underground can remain at all coherent is through mutual reinforcement. Without a network of other magicians, any single mage is little more than a schizophrenic — he has the power to alter the world, but it's either through coincidence (in which case it could have happened anyway) or invokes the unobserveed tree paradox (in which case nobody else knows that the world has changed). Remove that reinforcement, and nothing concrete stops our protagonist from being just another crazy person.
So. A loner, an outlier — some would say a "stereotype" — is engaged in some undercover work investigating a cult. The cult realise this. One of their members oversees treatment at a Place Without Shoes. A call to the police or ambulance and some expedited paperwork later, our protagonist is convinced that he's a schizophrenic with delusions of magic, and that treatment is helping him relate to the actual world. Any magic around said protagonist is just another symptom.
What avenues are open to the protagonist beyond those that he himself would classify as "self-delusional"?