...Getting lost driving home from a familiar place? Not good. But if you just flake out and make a wrong turn because you are preoccupied, it's probably okay. However, if you are driving home from a familiar store and can't remember how to get from point A to point B, it's probably time to see a doctor.
If you do have symptoms that bother you, see a doctor, for your care receiver's sake as well as your own. If your mother has Alzheimer's, you can't properly care for her if you can't keep her medications straight.
But make sure your doctor is aware of your stress level as a caregiver, since stress could behind your feeling that you may be "losing it." Other possible causes: