I Am 76 Years Young Female . I Have Had

I am 76 years young female . I have had for the last 4 days, unbelievable fatigue. This happens maybe once or twice a year since I was in my fortes. I get a funny warning that maybe just "for me." My head and stomach itch uncontrollably at night. This happens, then fatigue. I have now had a complete release of my bowels without and cramping. This has happened twice in the last two months. I am active. My husband and I just went on a zip line and also went para sailing. I take care of my home, do Thi Chi ride a stationary bike everyday. So having to give in to this fatigue is very new. My joints also ache during this time.
Please