I was interested to read that you think you know your son and that your gp friend openly admits that you know a lot more about your son's condition than her.
A while back we were out walking on Boxing Day with our two children aged 8 months and 2 years 8 months. The older child took a running jump at the pram and managed to pull it over on top of himself, falling awkwardly. Thankfully I was holding the baby at the time! There was a scream of pain and then a lot of crying, and he couldn't stand up or walk. I told my husband we needed to go to casualty because he had broken his leg. We put him into the pram and walked home. My husband was not convinced about needing to visit the hospital, but the child still couldn't stand on his leg and I remained convinced that it was broken. We waited for ages in casualty and eventually saw a doctor. He told me he thought it was his hip that was hurting and that he didn't want to x-ray as it wasn't safe in such a young child. He sent us home. That night I decided to call the emergency doctor and tell him that I wasn't happy with what had happened at the hospital. He said to go straight back to casualty. We waited again, and once again were told it was his hip. I said I was certain that it was his leg, but they disagreed and decided to x-ray the hip instead (despite it not being safe?). It showed nothing so we were sent home again. The next morning he still couldn't stand on his leg and was screaming with pain. In desperation my husband took him to see a physio he knows, and she advised us to take him to the GP. I called the GP for an appointment and was told they were fully booked and couldn't see us unless it was a real emergency like a broken leg or something! I said it was a broken leg and so they said to come immediately! The GP took a look at it and asked if we could pay to see a consultant privately. We said yes and so he booked us an appointment at the hospital immediately. The consultant took an x-ray (2nd one!) of his leg and said it was a spiral fracture! He was set in plaster for 6 weeks. Don't ask me how I knew that he had broken his leg, I just did! It is called women's intuition or a strong maternal instinct. It taught me a very valuable lesson - that I know best and that doctors should listen to me! Some time later my Chiropractor told me that when he was doing his medical training his professor told him that when confronted with sick children he should always ask the mother for a diagnosis. He says he always does this and the mother is always right!
So to all you mums out there - trust your instincts and don't let anyone fob you off, no matter how qualified they are - you know best!