First thing: don't freak out. If it is anything, it is most likely very treatable.

Back in 2005, the doctor found a nodule on my thyroid. I was completely freaked out until I started doing research and understood more what was going on. I was able to make a list of questions I wanted the doctor to answer and was able to make informed choices. I did end up having both lobes removed (a month apart because my single nodule did turn out to be cancer) in 2006. Everything has been completely clean since.

All I can say is to do as much research as you can and ask a ton of questions. You'll especially want to research and understand the function of the thyroid (and perhaps parathyroid to ask about the calcium issue). Do some research into nodules and treatment options. There is a lot of information out there.

What kind of doctor is he going to? A general practitioner, an endocrinologist, or an ear, nose and throat doctor?

Please feel free to post again if you have other questions or if you just need support.