if you are a girl, it could be cramps. a little ginger ale or coke will help. if not cramps it might be a muscle strain, take it easy for a few days and if you lay on the opposite side and pain kinda moves its stool issue
Why don't you ask a real doctor, instead of random strangers on the internet who have no idea what they're talking about. Would you really have surgery on your appendix just become someone here told you to???