Re: Just diagnosed with hypothyroidism and I have questions.
That's the trouble with most MDs. They think hypothyroidism is always a simple fix. More often than not, it isn't simple at all.
You are quite severely hypothyroid. Almost everyone who gets diagnosed still has free T4 within the normal range, but at the very low end. Yours is actually below range, and that's what marks the degree of severity. You didn't need to question the diagnosis.
Since you are so hypoT now, you've been deficient in thyroid hormone for a long time. This can cause weak adrenal function, which makes thyroid supplementation cause you to feel dreadful. Nausea is a key symptom of weak adrenals The thyroid hormone cannot enter cells the way it's meant to when the adrenal cortisol is low. There's a high possibility that you may need adrenal support simultaneously with the thyroid supplemenation. I can't tell you much about adrenal function other than that. Broach the subject with your doctor right away.
Another thing that can be helpful for starting treatment following prolonged hypoT is to begin with a very low dose of Synthroid and work up to a full dose more gradually. In cases like yours, starting with 12.5 or 25 mcgs instead of 50 can be easier on one's system.
I can't answer your question about vitamin D relating to calcium. But I do think it might be wise to ask questions about pituitary trouble, given the very high TSH and prolactin levels. You could be on to something there.