What Is The Reason For Extended Irregular Periods And Headache And Diarrhea During Periods?

Hi, I am 18. I had extended irregular period for almost three years. In the past, my period usually lasted for around 2 weeks. Sometimes it stopped at around 1 week and came back again after 2 or 3 days. Recently, my period reduced to 10 days, but I began to experience severe headache and diarrhea during period. I went to see my doctor before and had taken meditation regularly, but it didn't get better. Is there anything I can do? Thanks