Hi! R U still under the care of an oncologist or Cancer Nurse?
You may still be in shock which can be wearying. Be kind to yourself.
Once I had finished treatment for breast disease, I felt adrift once all my appts. had finished. I also got fed up with 'being brave' for everyone else
and would lock myself away some days 2 have a Very Good Bawl.
Menopause can play havoc with thyroid function I believe which may cause tiredness. Also lack of VitD so taking a capsule daily won't do any harm. Keeping a mood/food/symptom diary may B useful too.
Let us know how you get on. If U put 'kliofem' into the search box U should find threads to read.