It sounds pretty normal to me. There are many reasons why this happens. Read through the threads, especially the ones on UV light. Most stores have those and they are hard on you. I find they drain my energy and I have to sit also.
Try light exercise I start with 5 minutes one day and add a minute every other day to build up. Works for me might work for you. I used to clean only during the TV commercials. The house got cleaned and I wasn't too tired. Then I tired the one room per day technic. That worked also.
Try it it might work for you.