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I don't think you will see much from D2. Did you mean to type D3?

Both B12 and D3 will only work if you are low in them.

Since you have autoimmune disease, quelling that reaction is typically the way to go.

Without treatment to suppress the excessive autoimmune attack, healing will always be behind continuing damage.

Muscle issues will respond for the most part to magnesium use.
That will help the PN too. So think about a quality magnesium supplement daily.

We discuss magnesium almost every day here. Use the search function to see the most recent posts. Start with soaking in epsom salts, and see what happens and move on into oral or topical as you see improvements with the soaking.