Do you think you might just need a rest, with some peaceful, unplanned time for yourself? If your energy level is low at the moment and you have aches and pains, maybe it's better to take a bit of time out each day, if you can, and go easy on yourself.
There are some good alternatives to coffee if you think you're drinking too much. If your mood is low, can you get out to the park for a gentle stroll or have a wander in the garden each morning? I care for a family member full time and work part-time, but when I can get out, even for a short break, it really helps.
My parents weren't ones for complaining about tiredness either. They always seemed busy and productive but they wouldn't have prioritised their mental health.