Unusual symptom?

I was finally diagnosed with a muscle disease/disorder, non-specific, about 5 years ago after going to the neurologist for over 10 years. I have the muscle weakness, pain, double vision, etc.; but I have also noticed an increase in apathy. I understand how you feel has a lot to do with what you do, but it seems like my desire to ANYTHING is completely gone and getting worse if you can imagine. I can sit in my recliner all day with no TV, no music, no reading--just napping on and off and checking my phone. I have also been eating just one meal a day and feeling perfectly satisfied. I'm 74 years old and have been taking Wellbutrin and Duloxetin for pain and depression for a number of years. Is anyone else experiencing this apathy symptom?