What Can Be Done About Irregular Periods Which Only Become Regular With Medication?

22 Years girl irregular in mensuration period. It takes 2-4 times in a year since her age at 13. when she takes medicine prescribed physician monthly period get regular. When stop the medicine it became irregular. Last before 2 month she used Herbalife womens choice. then she attained the period after 20 days. But now no further period attained till taking the same nutrition. what is the solution ?