@grannny Stomach pain and diarrhea are known side effects of Co-Q10, but not fatigue or insomnia.
Perhaps you would like to get a complete medication review from a trained pharmacist or nurse, who can look at all of your medications (Rx & over the counter), dietary & herbal supplements (including any herbal teas) to try to find the source of your issues. They check possible side effects of each item, and all the possible interactions between meds, supplements, etc
Medicare covers this once a year, and I use a pharmacist recommended by one of my docs. Over the years, this has led to discontinuing or changing the dosage of several meds and supplements, and recommendations to my doctors for better options for a few of my health issues.
Have you ever had a full medication review?