See your doctor. This is not normal aging. Getting a Hypothyroid diagnosis can take years if you are one of the people for whom the blood test is garbage. Insist that your doctor get the full T4, T3 testing done. Sleep apnea is also one that can be hard to diagnose but leave you feeling fatigued.
You don’t have a husband or live in partner that might be drugging you? In this day and age, it isn’t as far fetched an idea as it once was.