I am 22 years old and got an unexplained PE about 3 months ago. Every time it seems like we finally coumadin level regulated, about 2 weeks after being on that dose my INR starts to drop again. I don't eat much with Vitamin K and have been regulating what I eat. Nothing seems to help. I'm already on 12mg and 15mg of coumadin alternating. Which is almost triple my grandmother's does and much more than any friends have ever been on.