What Causes Bleeding From Nose With Headache?

17 year old male - 6'4" = about 275 pounds or so - simi active - walks about two miles a day with dad and dog - and mows grass for two to four hours a week with a push mower - so not totally sedentary - nose bleeds - two to 4 a day for the last three days - two of which were sever and hard to stop - also had a bad head ache on friday last week ( four days ago) and his eye weeped all day - but he said it was from head ache - no nose bleeds at that time - next day his eye and head were fine - nose bleeds started that night - question - do you think it is sinus from the mowing or did he pop something serious - silly dweeb has gone to camp for a week -