Being a transplant patient, you want to be extra sure about any diagnosis, since invasive procedures can leave your already-suppressed immune system open to infection. Plus, you don't want to miss the early signs of a correctable problem. I also think you should see a second doctor. There's no harm in it at all -- your first doctor doesn't have to know if you don't want him to, and you can always go back to him if you want. If this first guy isn't used to seeing immunosuppressed patients, maybe someone involved in the transplant unit would be a good choice.