Hi,,my Period Is Irregular.but Nw I Have Periods.but That Is

Hi,,my period is irregular.but nw I have periods.but that is not Normal,because some time no blood,some time little like that,.then I consult doctor,she advised norethisteron acetate for 5days,then she told come back to day second.I didn't understood.my question is second day means,if I am taking norethisterone after that period will start,then second day know