Hello.
This pain is most probably a muscular pain. But you should also consider an internal organ problem which may manifest this way.
I suggest you visit a physician and get yourself evaluated for this problem. You might need to get a ultrasonogram done to see if there is any problem with the abdominal organs.
Regards
This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one.