What to do about this exhaustion!

Hey guys! I've noticed that the past few months that I've been fatigued and tired most part of the day. I used to be in school and working overtime as a waitress but now I have a relaxed life at home as a housewife. In the morning I feel tired and don't feel like getting up. I can do a few task through out the day but after those few things, I feel exhausted. I was concerned about this problem and have seen many medical doctors. I am fine. My vitamin D levels are low. I do suffer from fibromyalgia, but other than that, I am relatively healthy. I try to exercise and sleep well- this is what most helps my fibromyalgia. Sometimes after I do pole for an hour, I feel like laying down and sleeping. I would really appreciate some advice. How can I get my energy levels up? Does anyone else suffer from this fatigue too?