Hi, I Am 14, I Weigh About 135 Pounds, And

Hi, I am 14, I weigh about 135 pounds, and the only serious medical condition i have/have ever had is high cholesterol. I have been having pain in my lower abdomen for just about an hour today. It is a sharp pain, but not localized to either side, almost right below my belly button. it is made worse by breathing in deeply or sucking in my belly. Also by standing, and twisting my body around. This has happened before, but not often. It is random, turning up occasionally after I eat, sometimes when I just wake up. It is the same thing every time. i usually just bear through it and it has disappeared within a few hours. Could this be appendicitis, or simply bad menstrual pains? Thanks!