Your D3 is severely deficient. I was at 19ng/mL in September and will retest my blood in a few weeks.
You can get D3 in a liquid if you don't like to swallow pills
US lab range is 30-100ng/mL. You need to be above 50ng/mL. Anything below should be considered deficient.
D and magnesium deficiency can cause depression, fatigue, anxiety, pain, brain fog, headache, eye sensitivity, etc.
You need Vitamin D3 supplements, magnesium and Vitamin K2 (as long as you aren't taking medications that would conflict with K2).
You could start at 5,000iu D3 daily for a few days to see how you feel, then work your way up to 10,000iu daily. Even when you get to corrected levels, you need to supplement daily. D3 does not stay in your body.
5,000iu is more like anaintenence dose. You must retest your blood after 3 months to see where your levels are at.
The only blood test that can diagnose vitamin D deficiency is a 25-hydroxy-vitamin D (25 OH vitamin D). Unfortunately, some doctors are still ordering the wrong test, 1,25-dihydroxy-vitamin D.
Magnesium is essential, you need to take it with your D3. Take D3 with some sort of fat (like coconut oil, avocado, peanut butter, etc. it helps D3 & K2 absorb). Take D3 in morning or afternoon. Not at night. It may keep you up.
Vitamin D deficiency can cause a lot of possible symptoms. I'm not sure if this deficiency is a direct cause of nausea but vitamin D is essential for calcium absorption and calcium deficiency may cause nausea.
One of my signs I need more calcium (since I eat enough calcium in my diet this means I need more vitamin D) is the chvostek sign. If you want to check out a demo on youtube search: Positive Chvostek Sign showing Low Calcium Levels.