I am 80, and had a hip replacement 3 months ago, which has slowed me down, somewhat. Even so, it seems that I have a lot more energy than you. I have about 7 hours sleep, and rarely have a nap in the day. I am managing to get more done, now that my mobility is improving, but housework is not top of my list. I do what has to be done to keep the place reasonable, but my motto is definitely ‘dust if you must!’
I’m glad that you are going to get a medical check-up, as it sounds as though something is slowing you down. If nothing shows up then perhaps you need to do less housework and more fun activities. The main thing is to listen to your body, and don’t overdo it. Good luck, and I hope that your get up and go soon comes back.