As I understand you are 29 years of age, and have noticed bloodstains in undergarments in morning, without any other symptoms. The condition may result from local conditions like boils, bites or cuts, or you may stain your undergarments with blood carried from your partner after an act of intercourse. Once these are excluded, the reason that needs a look at is bleeding from urethra for which an endoscopic examination may be required. Any bleeding from the kidneys or bladder would also colour your urine and not only the undergarments. A Urine routine examination may exclude any blood present in urine.