Periods late by 4 days, though i am taking duphaston for pco. pregnancy test came negative. got back&knee pain, brown discharge, gas & stomach cramps.

PCO: You did not say how often you are taking that medication. If you are taking it on a daily basis ir just for 5, 10 or 15 days. Always consider pregnancy if you missed your period. If pregnancy, it might be too early to show a positive pregnancy test. However, depending on how you are taking that med, periods might be normal or very light. More info is needed to help you more.