This question is difficult to answer because I am only being presented with your view of the situation. It may be that from your standpoint you felt that everything was fine. Perhaps you saw yourself as compliant and “easy to get along with”. Your doctor may have judged this situation differently. It may be that he found you to be noncompliant with his suggestions, argumentative or stubborn. He may have felt that there was little or no help that he could offer you. I am speculating, of course. I have no way of knowing if these statements accurately reflect how your doctor felt about you.
If he “fired” you for no apparent reason, then this was unfair. At the very least, he could have offered you an explanation for why he stopped seeing you.
If he did in fact stop seeing you because he found you to be difficult to work with, then this may be for the better. It might not have been helpful for you to remain in the care of a doctor who felt that he had no more assistance to offer you.
You also mentioned that you signed yourself out of the hospital after deciding that the staff was unable to find you effective help. You wrote that you felt that you could do a better job at finding your own treatment. You then left the hospital “against medical advice” (AMA). From a mental health professional’s perspective, some may label your behavior as “difficult.” Many mental health professionals (rightly or wrongly) might perceive this action as a sign of an individual who is unwilling to heed professional advice and would prefer to handle situations their own way.
Please know that I am not saying that you are a “difficult client” or someone who disregards professional advice nor am I saying that if an individual leaves the hospital AMA, they are doing something wrong. What I am saying is that leaving the hospital AMA may be a red flag for some mental health professionals. It could be that your doctor felt that leaving AMA meant that you no longer wanted or felt that you needed his advice.
You may never know why your doctor “fired” you. You could ask him or move on to another doctor. I know that finding a new doctor may be challenging but it is what you should do. Take care.