HI Well come to HCM I had gone through the history given by you and I could say that it may not be pain due to hormone changes because of the age (The typical dysmenorrhea ) but it seems to be the pain due to certain common illness like, colicky pain due to alimentary disease, smooth muscle spasm, urinary track infection may be associated with renal stone. Work up:- Ultrasonography, plain x-ray abdomen, Treatment:- If this is the constipation then you have to start eating more fiber containing diet, drink more water. Medication:- Dicyclomine tablet with Acetaminophen can be tried only if the pain is severe, else the final line of treatment can be judge after final diagnosis. Advise:- wait and watch would be the first strategy, pain will go on its own