Suggest Treatment For Irregular Periods

I experienced irregular cycle and was given m2 tone by my doctor to take for one month. During the period I was taking the drug, I had the correct cycle and my menses came even a day before the actual date. But after the drugs the cycle has become irregular again. It took 32 days before I had my last menses and now is been 36 days and am still not having it but going through the normal symptoms I go through before it comes. What could be the cause and how can this be corrected?