For those trying to raise Vet D levels be sure you are doing it correctly and please be aware you can harm yourself if this isn’t done correctly .
If you don’t take your D with fat then it won’t be absorbed. Its best to take it several times during the day and always with fat. If you D is 30 or above then you are normal.
If you are having issue with low D and other nutrients then you have issue with absorbing nutrients , most common cause is Celiac but see a GI doctor you may need some testing.
Vit D also can relate to kidney function as about 30% of the people who donate kidneys end up with deficiencies.
Have you had Thyroid antibodies tested as that goes with low D.and thyroid issues.
B12 injections should only be given to people with pernicious anemia.
Really sounds like you need a better work-up.
Too much B 12 will cause neuropathy.
Be careful folks with the supplements you take.
See a Gastroenterologist for nutritional deficiencies not a Endo.
Have you had Ferritin tested and iron sat?