Can stretching cause the hymen to break? because one day i was doing sport i didnt have any blood in my underwear or vagina and after a few hours i constipated and i had discharge with some blood spots.

Probably not, but...: Only in cases of alleged sexual assault upon girls and women do we physicians engage in the careful examination of hymens, collecting evidence of physical damage to be used later in courts of law. In normal everyday life, people should not be "checking hymens" nor thinking about whether they are broken or not broken. As good citizens, we must prevent discriminatory treatment of girls and women.