Ask the doctor: My daughter is unwell a lot but nothing is ever found. The GP says she has health anxiety. How can I help?

Question: My daughter seems to have all these health problems but when she goes to the GP, she feels she isn’t being listened to. She was always a bright and happy girl but since she hit her mid-30s and everyone else moved on and got married, she started getting pains and despite numerous tests and scans, nothing has shown up. She told me that the GP thinks she is imagining it and that she has health anxiety. Can you explain what this is to me? And what can I do to help?