In my experience, most doctors who say your pain is all in your head, you're just ruminating over your suffering which in turn makes your pain worse, don't really know why this happens. Most respond with some banal anecdote about stress -- which, might I add, is infuriating. So, how do you respond? How do you 'change' their minds? In short, you probably won't be able to totally change their minds, at least not during the five or ten minutes you see them. You can, however, make them re-think their position by questioning the legs of their suppositions. Here's how.
When your doctor claims stress is causing all your pain, ask him how. Ask him to break it down, chemically, and show you the physiological proof. If he cant, you show it to him.
Doctor: "well, your pain doesn't really correspond to any peripheral injuries that I can see. You're young, you look healthy. Its possible that your pain is all in your head, or at least caused by stress."
You: "What do you mean? What is stress and how can it cause my symptoms?"
Doctor: "There have been many studies done on the effects of stress on daily functioning and pain"
You: "But how is that possible? What happens?"
Doctor: "It just does"
You: "how can something internally cause an abrupt and significant change to my homoeostasis that signals the chain of events which manifest themselves in these 'effects of stress on daily functioning and pain' that you speak of?
Doctor: *disparaging and condescending look; maybe a roll of the eyes.*
You: "If you don't even know how stress manifests itself, how can you know for certain that its the cause of my problems. Aren't you in effect saying that since there's a lack of information and proof to substantiate my claims we'll just go ahead and assume that your position is by default true? Isn't that a fallacy of ignorance? "
Doctor: " The long-term effects of increased cortisol levels can cause cumulative destruction of neural tissue."
You: " I know that hypocortisolism can have drastic effects of muscle and bone, and this depletion of cortisol is caused by prolonged stress. I also have studied the programs of neural, hormonal and behavioural activity which aim at returning normal homoeostasis. Don't these all represent significant biological changes, not psychological abstractions which insufficiently 'explain' pain? Aren't even the psychological process which can cause pain 'caused' by signal transduction pathways which are in their very nature biological, and since you are assuming that only true biological processes are legitimate, then aren't the psychological explanations you proposed legitimate? "
This could go on and on, and could pan out multiple scenarios. The fact of the matter is, you can't really claim your doctor is inherently wrong when he questions the origin of your pain, if you don't yourself know (at least in some form) the origin of pain. He is a doctor, and he that title does deserve respect -- respect is not tantamount to increases or decreases in value, though (respecting him doesn't mean he's a 'better' person).
If you are the type of person who is willing to wait and doctor search for a physician competent enough to know something is going on, then this probably doesn't matter to you -- although everyone who suffers from some form of pain should know a little about pain. For those of you who aren't very patient, and really take these blows to heart, then knowing why your doctor is wrong could really help. If your like me, when doctors say pain is all in your head, it uproots the basic stability we have worked so hard for. I'm left questioning why I think I'm right for weeks; finally I come back to my initial position, though. Its understanding why you come back that matters. If you know why your doctor is wrong you can prevent these events from happening.
You may not be able to change your doctors mind, but you will definitely make him re-evaluate his position. This knowledge will help you personally and pragmatically. I encourage everyone to have a basic understanding of the chemical, biological and psychological aspects of pain. Its a war out there, we need to have some preparation or else we'll be quickly defeated.
The important thing to remember in all of this is humility. What angers and infuriates us can easily be converted into a weapon or tool for our defence. When a doctor is condescending and rude, returning condescension and rudeness defeats the purpose of even trying to change his mind or explain yourself. To him, you become a rude and condescending person (much like the rude and condescending person he is to you). You fear he thinks you're a weak person who 'causes' their own suffering and thus deserves to be left alone. If you respond in keeping with how he treats you, you breathe life into this self-fulfilling prophecy. The key: be humble, civil and forthright. Treat others with respect, even if at times you feel they don't deserve it; people respect these qualities.
“Deep is the well of truth and long does it take to know what has fallen into its depths"
-- Nietzsche.