Sudden sharp pain (4/5 on pain scale) just above belly button. no recent antibiotics or exposure to illness. what could be the cause/possible problem?

Belly-button pain: Belly-button (umbilical) pain may originate locally due to infection or herniation, or be "referred" from another abdominal location like the appendix. Signs/symptoms of concern include: local redness ; drainage, umbilical bulging that can't be reduced with gentle pressure, fever, vomiting, change in bowels, generalized abdominal tenderness (suggests peritonitis), worsening pain--get checked pls.