What Does Frequent Nose Bleeding After An Accident Indicate?

ey. my son fell on his nose 3 months ago and had 3 stitches there. did an xray too and doctors were afraid the cartilage was broken but when physically examined they said he is fine. one month after he fell his nose started bleeding on different occasions , when he has cold his nose would bleed at least once (sometimes twice ) during the day. if he is hit or he fell n his face or nose he bleeds . i have checked different doctors and they all said that the vessels became more sensitive after this incident that is why he bleeds .. what shall i do ? is this true ?