Joint pain with redness. B12 in range.

I have highly fluctuating thyroid,which ranged from level 65(recorded at the time of pregnency) to 0.01 (current level) in last 6 yrs. I am taking 75 and 50 mg thyroxin (alternate days). I recently recorded low vitaminD. From last 2 years I am facing body pain especially near limb joints. From last 1 year it has increased to level that I am unable to straighten my hand atleast once every month, it automatically get corrected in less than a week than the pain shifts to back of the hand and top of the foot and near/above the knees. Atleast 5 times I also have to faced mumps like issue. In winters my hands get completely numb and start turning dark red and back of finger tips turn blue, though hemoglobin is at 10.8. Currently my index finger's upper joint is dark red with a small bump, it sometimes feel inflammable, my hands are stiff and other finger joints are also paining.with this I m also facing dry mouth. All this due to lack of vitamin d or is it arthritis. Sugar, b12 in range.