When I suffered greatly from motion sickness, I remember various people looking very annoyed with me, saying things like:
"It's just in your head. Stop thinking that way.Your're just doing that to yourself. "
It's just in my head?
How does saying that help any? I am pretty sure all pain is sensed in the head. It gets sent there from all over, but the brain gets the message and acts on it in the same way.
When someone says that, it seems like they are trying to deny the reality of my pain. While "It's just in your head" may means a false message has been received and that no damage actually exits, the signals and consequences of those signals feel very real. They still have to be dealt with. Saying the origin of the pain is not legitimate, while the experience of the pain is the same as any other pain, does not bring about any relief.
I think it works out better for everyone if the feeling of pain is acknowledged and something like this is said, "I'm so sorry you feel that way. Can I do anything to help?