It could be one or the other, or both? … I know breaking the fast with certain foods can cause this, and I’m sure like everything else in life, we are all different, so it could just be the Wheat Grass Juice, as you stated.
I know I’ve seen some say they like to break a fast with eggs and bacon, but for me, eggs set me off. Not sure on bacon, but since it did it two times in a row, I now just use a small spinach salad with olive oil and dressing. Since this works, I’m sticking with it. … Hope you find it which is was, or find something else that works for you.