It's my lower left stomach not my right and i didn't feel it above my belly button im 14 years old in a half I'm a female, I'm on my 2nd day of my period and I can feel a weird sensation on my lower left stomach and when I touch my stomach it feels like a heartbeat. What could this be? I know I'm not pregnant, I haven't had sex yet. Could it appendicitis or AAA? Thank You for your help! I would also like to know if it's just in my head? But I swear I can feel it and I don't want it to burst I do have one of those sickness?!