Have you any medical scientific evidence to support that claim?

What level of 25(OH)D do you regard as optimal?

Given 125nmol/l or 50ng is the level at which the body starts to store D3 and at which human breast milk is replete with a natural level of Vitamin D3 what are your reasons for suggesting any amount lower than that is acceptable.
If vitamin D deficiency makes fibro pain worse then correcting that deficiency can only help. The only research I have seen regarding Fibro pain and vit d used Ergocaciferol and as we know perfectly well many people cannot tolerate D2 and many others cannot utilize D2. We must regard with the utmost suspicion the ethical integrity of any research done on Vit d that uses an unnatural, synthetic, form of the vitamin when there is cheaper more effective more reliable and safer alternative.

The case against ergocalciferol (vitamin D2) as a vitamin ...