Vaccines and/or air pollution. Other cause may be lack of solar radiation, for whatever reason.
Take vitamin D, lots of it.
Discussion
Do not megadose vitamin D.
any amount above the RDA is useless to your body and your kidneys will have to process it. Sometimes this causes a buildup of a chemical that forms hard sharp crystals. These are kidney stones and they are painful AF.
(that said, low doses of vitamin D are great, especially in countries where there isn't a lot of fish oil in the diet. here in the States they add it to milk so most people are covered if they make pudding or have a bowl of cereal now and then.)
Sun is great too 😁 ☀️