What Causes Left Rib Pain And Stool With Blackish, Circular Spots?

All day I've been having a slight pain just under the left side of my ribs, like a slight muscle pulled feeling to it. However, I just passed stool that had at least two spots in it that were circular, blackish, and obviously a different consistency than the rest of the stool. I've also eaten a lot of fish in the past two days, and at least one bottle of red wine, which is to say out of the ordinary in my routine.