Extreme pain during period

When I had my period on Monday, I was dealing with extreme pain, I couldn't even move from so much pain and I had to go to the bathroom constantly (Period Diarrhea and a LOT of blood.... Like a crime scene....). I couldn't even focus on my homework the entire day. I had the same exact pain yesterday since it's my 4th day, where the horrendous problem happened at school, meaning I missed class to be in the nurse's office. What should I do to stop this horrible pain? (Btw I already take pain killers and I don't have access to birth control)