Pain on the right side across from the bellybutton
My friend asked me to help her with a problem she's been having. She was out and asked me to research about some pain she has. It is continuous pain for. She said it was perpendicular to her bellybutton on her right side. Out of 1 to 10 she said it was about a 7. Her mom says it might be a pulled muscle but she wants to be sure. If it helps, she is an somewhat young teenager. Can anybody help?