Why did you stop taking D3? what was your D level when you stopped?
Vitamin K2 is formed by bacteria during the fermentation process. Natto has the highest amount naturally around 1000 mcg per 100 grams. A typical serving of Natto has 45 grams. Hard cheeses such as Gouda & Jarlsberg have the next highest, but note how much lower at 76 mcg per 100 grams of K2.
- https://www.nutritionadvance.com/foods-high-in-vitamin-k2/
The recommended daily intake of K2 is 90 mcg, but studies have shown 200 mcg per day is necessary to prevent calcium deposits in soft tissues (arteries, renal, etc.). I take, on average about 400-600 mcg per day because I eat Natto most days. Natto is an acquired taste.....like scotch. You have to watch others do it knowing it's good for you and then you dig in and in and in and finally - oh -yeah, this is why people like it. Natto is like that. It has a nutty flavor and once you get past the smell and texture - the flavor comes through. Like blue cheese.
Most people will opt for supplements. Make sure you buy supplements that are MK-7 which lasts longest in the body. I take a full spectrum K2 (i.e. mk-4, Mk-7, mk-9) which has a minimum of 100 mcg of MK-7. I consider supplements a base level and when I add Natto, I am supercharging my K2, but never below 200 mcg per day. My arteries cleared out in two years!
K2's effect is dose dependent. The more you take the more osteocalcin you produce which binds to excess calcium and removes it from soft tissue and in concert with vitamin D deposits in bone.
Vitamin D and K2 work together. https://www.grassrootshealth.net/blog/need-take-vitamin-k2-vitamin-d/