My son 13 yrs old has blood present in phlem produced by coughing and blowing his nose. We have been sick for a while though not consistently. He brought a cold home from school shortly before winter break, he recovered mostly after passing it to me but came down with it again after it made the rounds with my parents. He has some significant allergies and pollen has been high so there has been a lot of nose blowing. He is also not the best at coughing up what s in his lungs despite urging. There are no other signs and other than then running nose, a slight sore through which has since cleared and an occasional headache, he presents no other symptoms. He is rarely sick so we have never experienced this set of symptoms previously. Is this something to be worried about or merely the result of frequent nose blowing and coughing?