Thank you all for your comments - I took each one to heart. After finally making the decision to get Nate and the girls vaccinated; Nate came down the croup this afternoon. He woke up from his nap all croupy with labored breathing so we went for our appointment (I had moved up the shot appointment so I wouldn't chicken out) and he was officially diagnosed with croup. Emma and Sophie both got the mist and they rescheduled Nate for Friday at 9:00 AM.
Again, thank you for all of your comments and words of support.
Now, we will see how I survive the night with a croupy, diabetic, grumpy baby boy!