Pooping blood...

I'm not sure if this is what's going on but I had seen a few of Milla K's videos on YouTube. She had the ROU-en-Y gastric bypass surgery and she talked about in her video on her first day back home how her doctor told her she'd poop and it'd be really dark from left over blood.  I mean, I'm not sure if your sister's poop is just looking bloody or just looks really dark...kind of bloody but hopefully that's what it is. I hope your doc has given you all a little more direction or was able to find out what the problem is. Sending prayers your way.