I Am Now Two And A Half Weeks Late For

I am now two and a half weeks late for my period. This is the second time this has happened. I completely missed my November period and didnt start it until December 1st. That is the last time I had it. I have always been extremely regular. I have a coach helping me with the Billings natural family planning method. She suggested I reach out to a doctor after I told her that my breasts have been very tender, I've had boughts of nausea and that my discharge has a bad odor. Both have never happened before, so something is off. I lead a fairly stressful life but not anything too different recently. Maybe its built up over time and just now affecting me? Hahahah!

Any advice would be awesome!
Thank you so much