Would I be crazy if I got my whole body tested for cancer after being diagnosed with thyroid cancer?

My thyroid cancer has spread to 4 lymph nodes in the lower central area of my neck(below my thyroid). I don't think I have any other type of cancer just because of my thyroid cancer, but melanoma, ovarian and cancer runs in my family(not even thyroid cancer). Would I sound too crazy if I asked to get tested for other types of cancer?