Unusual Pain during Periods. Situation?

Her period has started on 25th Aug now, but she is having unusual pain which she never experienced before. Suddenly a lot of pain occurs in between vaginal and belly button. Pain is so hard to bear that she had to take painkiller also. Unlike before period bleeding is also coming very low this time, like its 4th or 5th day of her period cycle and bleeding is about to stop. She took contraceptive pill in the morning of 25th and we had unprotected sex and periods get started after two hours. While she gets period we again had unprotected sex. Her last period started in between 25th Jul to 29th Jul, 18th Jun to 22nd Jun and 14th May to 18th May. Her normal period cycle varies in between 30 to 35 days. Kindly suggest why she is having unusual and unbearable pain which never experienced before and why period bleeding is not coming properly? Do she needs to visit hospital or can wait until period cycle ends.? If needed which medicine should she take in this situation?