Can vitamin d deficiency cause fatigue or depression/anxiety? i am especially concerned with the fatigue. my blood level was a 10.

Yes, it could: Yes, vitamin d deficiency could cause fatigue and depression. Talk with your doctor about replenishing this. With your very low level, you may need high dosing with it temporarily, and then back off to a maintenance dose. Please be aware that it's also possible to have multiple conditions at once, all of which need treatment (depression, anxiety , and vit d deficiency, etc).

Certainly: If your hemoglobin was 10, then you have an anemia, diseases that cause anemia, including vitamin deficiency (b12) can cause fatigue, depression, anxiety. You need a careful examination to find out what is the problem, including checks for cancer, inflammatory diseases, vitamin deficiencies, ulcers, other bleeding states, etc., particularly with the postural tachycardia. Schedule it this week!