Pink to brown discharge half way through my cycle. cycle is usually like clockwork. 28 day cycle. am now 3/4 days late for period. negative pregnancy test on sunday afternoon. no other unusual symptoms. what could this be? never missed a period.

Tests are accurate: Today's home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, or medications. A correctly done urine test will give a reliable result 3 weeks after sex (3 weeks after possible conception) or 1 week after missing a period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon.