Painful period with back and shoulder pain and diarrhea?

Cannot diagnose. The symptoms you have provided may or may not be in sync with one another, and in addition would have to see you face to face and examine you in order to assess this. See your family doctor, and in addition, answers on healthtap aren't intended for individual treatment, prescription or diagnosis.
Is it your norm? If. yes - NSAID’s, SSRI’s, hormone meds, OTC meds containing diuretics, warm bath, heating pad, exercise & acupuncture are excellent for PMS / period. Avoid caffeine, chocolate, alcohol & salt. Get GYN eval to R/O underlying pathology. Consider omega- 3 fatty acids, magnesium (supplementation or through diet) or Black Cohosh with dr ok. Sipping Chamomile can dissipate pain. Ginger helps w nausea.