These symptoms strongly suggest severe menstrual cramps (dysmenorrhea) accompanied by nausea. For the pain, over-the-counter NSAIDs like Ibuprofen (400mg) or Naproxen can help reduce uterine cramping, and are most effective when started just before or at the onset of your period. For the vomiting, a doctor can prescribe anti-nausea medication like Ondansetron. Because your pain and vomiting are severe, please consult a gynaecologist or healthcare provider for a proper evaluation to rule out conditions like endometriosis and to get appropriate prescription-strength medications. Meanwhile, stay hydrated with small sips of water or electrolyte drinks, and apply a heating pad to your lower abdomen.