I introduced raw blueberries to my 8 month old last week. she liked them. I would mash them lightly and then mix in with plain yogurt or just bite them in half and feed them to her on their own. by the 2nd day she starting grunting and shaking in pain whenever she was pooping. This got much worse by day 3, to the point that she was crying so badly to poop. She was still pooping regularly but it was hard and blue! So i cut out the bluberries and went back to applesauce and pear.

Is this a common reaction? could be anything else causing this problem?