my periods are irregular since last decembr,in decembr n january the bleeding was just like spotng n then next two months i got no periods, after i took primolut nor n got normal periods in april but next month again started on same date but light bleeding,june no period, july one day after intercourse i noticed very little red blood when i wipe,now almost 10 days n stil spotng, for last 2 days thre was very light brown discharg which stop in morning, so we try to have sex in afternoon n again very little red spotng startd again.what is the reason.