Re: 11 year old bleeding ulcer?
Ulcers aren't caused by stress, that's a myth. They are most commonly caused by an infection called H. Pylori, and, yes, they can happen to children as young as she is, although that's rare.
Still, ulcers usually produce sharp pain in the belly. Often it's just below the ribs on the left side. Brownish blood on the toilet paper, or even a little bit in the bowl, could easily be the beginning of her first period.
See what happens in the next couple days.