Do I have an internal bleeding?

I started my period 2 days ago, pretty late at night. Everything is fine, I have cramps etc (the usual stuff). I'm someone who eats quite healthy, I always start my day by eating fruit, I usually like mango's, watermelon and blueberries. Now here's the disgusting part, ever since this morning my poop has had this black/grey/blue ish color... It's not even a lot, more like diarrhea consistency. I've looked it up and there are so many things that show up, it kinda freaked me out... I've read that eating too many blueberries can cause this, but I don't think I eat that many blueberries? I eat like 1 little box of blueberries in the morning with the rest of my fruit, been doing that for like weeks and never had any problems. Does this mean I'm having an internal bleeding or is it just coincidence and the combination of being on my period? I'm super worried... :/
Do I have an internal bleeding?
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