When did you last have a full blood count?
Tiredness can be caused by thyroid problems and low blood sugar feelings: my worst symptoms : can be eased by eating every 3 hours, even in the night. It's every 3 hours, 24/7 ;-)
Tiredness can be caused by low VitD levels too. Or hormonal upheaval. Some find it useful to keep a mood/food/symptom diary to chart progress.