Serious help needed!

Alicia
I know that (probably) none of you are doctors but I'm asking for advice anyway. For the last year or so I have had problems with painful sex. It doesn't hurt in every single position. Just ones where he goes in a little deeper. But it hurts extremely bad. I have been to my dr about this and talked with him numerous times and all he says is "it's all in your head. There's nothing I can do for it" 
So basically... What do I do? I love my doctor and have always trusted him. He's done great with me. But this just doesn't seem right to me... I love and trust my husband with everything I have and I can't even begin to understand how this could be all in my head...
Have any of you experienced this?? I am beginning to get extremely worried since it has gone on for so long... It obviously hurts my sex life when I have to tell my husband to stop because it hurts... Sometimes I can't even continue...