Can low vit d level of 30 cause one to be extremely exhausted & body aches even after sleep 8-9 hrs. i go to bed at 930pm & get up at 630am. i got covid in dec2020 & my fatigue is just getting worse. no doctors can really seem to help me?

Yes, low vitamin D can cause fatigue and muscle weakness among other issues. Since one seems to have the post covid long haul syndrome one is encouraged to self care - like in other chronic post viral syndrome: Eat healthy, especially protein rich and complex Carbs energy foods. Daily multivitamins plus extra Vit. C, E & D. Doctors who handle Chronic Fatigue Syndrome should be consulted.

Vitamin D level of 30 is normal, not low. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water. Wish you good health!

Long COVID-19 fatigue is well described and may respond to a number of medications used to treat fatigue associated with other conditions (such as ritalin, Nuvigil, modafanil, etc.). Aerobic exercise will help, as will getting Vitamin D-3 levels to about 50-70 ng/ml. Might investigate quality of your sleep via overnight sleep study to be complete.