Recently started having black stools, have stomach pain as well.

Likely: Time to see a doctor. Black stools may reflect only what you have eaten, or could be old blood firm stomach gastritis or an ulcer. I cannot tell what it is on this online forum. Needs a physician examination.

Ulcer: Black stools and abdominal pain usually point to a bleeding ulcer in the stomach or duodenum. Sometimes could because by cancer. Would recommend evaluation by your physician. Stools can sometimes be black as well from taking pepto-bismol.