i'd say that this time of year you both need to be outside. i have no idea what vit D does in mother/fetus situation. But i know for sure that whatever the baby got then isn't working for her now, and your milk is deficient. if a mother i low on vit D, so is her milk. So, go outside, just until you start turning pink. Then you made all the D you will in that day. Don't bathe for at least 12 hrs, or you'll wash it off. Repeat