Hi dear friend and thanks for posting this question and thanks so much to Roosplace for commenting.
I agree with Roosplace that those symptoms are associated to low blood pressure although it may be some further and deeper problems. One of the first symptoms of blood pressure is that when you are moving your body weight in a sudden form lets say standing up or coming our of bed your blood needs to get adjusted to the new imposed activity and if you experience problems with low blood pressure that is clearly one of the symptoms. Although it could be an iron deficiency you are mentioning how you have vitamin D deficiency and a combination of several deficiencies that could be causing the problem .
First you should check with your doctor about these symptoms but also I would like you try these two instructions:
Exercise and meditation:
Try to meditate: Sit in a quiet place, it could be a chair and breathe deeply for 25 times trying to focus in your breathing.
Then slowly stand up and keep breathing for another twenty times,
After that try to clap with both hands at the same time you are raising one leg for ten times making sure you are breathing properly.
Write down how you feel and share with your doctor, although you should always check with your doctor before you engage into any physical activity.
Hope this helps