Is Buclizine Hci Multivitamins Prescribed To Start Periods?

hi im twelve years and im not having period for 2 months. if i did i only have it for two days and a super duper little amount. then we see a doctor and the doctor gave me buclizine hci multivitamins. is that for period? and i found out that my moms told her secretly to give me weight gain pills. i don't want to gain weight. will i still drink the vitamins?