My stool was soft and exited fast but still had shape but little paper like pieces around it. Is this diarrhea? It only happend once, been constipated

Possibly. Diarrhea can be described in many ways. Sometimes by the stool consistency, and sometimes by the frequency. The definition is definitely relative and individual. What might be frequent for one person, does not constitute the same thing for another. What defines diarrhea is based on your own baseline. As to what caused the change in bowel habits, that is a complicated answer.