Ok, my 13 year old grand niece has had two nosebleeds this week. Apparently for no reason. She plays sports, so I thought she had been injured/hit/etc. but she says she has not been wounded in any way. The nosebleed was bloody, of course, but also had tissue in it. I know that sounds odd, but it was tissue of some sort. Today, she had another one. My question: what could it be? She is athletic and otherwise healthy.