I'm pooping black and light green is this bad?

Not necessarily. The color of your stool is affected by what you eat. If you had peptobismo which has bismuth. This will make your stools black. Stool can also be black from gastrointestinal bleeding. Digested blood looks black. If you eat lots of green leafy fibrous vegetables, your stools could look greener. The bigger question is are you having diarrhea, i.E more than 3 stools or watery stools a day.