I'm 51yr Old Female. Haven't Had Menstration Since End Of

I'm 51yr old female. Haven't had menstration since end of July. Thought I started menopause. I have constant hot flashes and night sweats and headaches but recently stared with chills, low grade fever and constant fatigue. Can't stay awake for 2days now. I am in great physical health. I work out 6days a week and can't manage to do that the last several days. Wondering if I should get checked out. Or if this is