Well, now that you mention the K2. I was taking a good brand, which I won't name, but it's Vitamin MK-4 & MK-7. I've taken this several times as well. Anyway, a couple of weeks ago, I had heart palpitations, so I started researching it and some folks have had problems with that while taking Vitamin K2. I stopped that one for a few days, then went back to my other Vitamin K2 MK7. It's a different brand. So far I haven't had any problems.
I sure was hoping that it wasn't the iodine, but it could be. But since I stopped that other K2, it hasn't happened again.