What Causes Menstruation Only When On Medication?

hello, sir I am getting menses problem at least from 2 years. I get through a some extra ordinary problem which still i do not understand why it was happen. there are 3 months which are not in memory. after that i find myself i am not getting my menses, I go to doctor, she give me some medicine with medicine I start to get my menses and when I stop talking medicine I get my menses for three months and after that those were again stopped, I start to take medicine and I get menses and one month without medicine also what this month I again did not get those. Doctor say my prolactin is high. I want to know is it this problem is curable or not. I am 28 unmarried.