Could Holding In Gas Cause Stomach Pain And One-time Black Stool, Or Is It A Sign Of Internal Bleeding?

For the past few weeks my stomach would hurt coming back from school, perhaps of me holding in gas / not passing gas when my body wants me to. But today I noticed for the first time I had black stool I m not sure if it s my internal organ bleeding or not. If I have normal brown poop the next time is it safe to say I m okay?