There can be doubt in your head and still have faith in your heart! Pain, symptoms even physical evidence all impact the head/mind. But it's what comes out of your heart is that which determine what lives in your life. This will get our minds right! http://youtu.be/DLWyAobbL9s
And Jesus answered them, “Have faith in God. Truly, I say to you, whoever says to this mountain, Be taken up and thrown into the sea,’ and does not doubt in his heart, but believes that what he says will come to pass, it will be done for him. Therefore I tell you, whatever you ask in prayer, believe that you have received it, and it will be yours.