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can be due to hormonal
imbalance ;anaemia;ovarian cyst
or any other cause so it will be better to get examined if needed get investigated and consult a Gynaecologist and she will help you.Physical examination is better and then your Gynaec nay prescribe the necessary medicines.The tablet you are taking is a hormonal pill and can be used to regulate the period but continuous use can lead to hormonal changes;weight gain;altered periods;bleeding or spotting in between periods;nausea;vomiting
to name a few are the side effects.So the best way is to consult a Gynaec and take medicine as advised for a specific period and then discontinue.
Although you have put up this question by name of Dr.Tayal i hope the answer i have given you helps you .