When to worry about persistant nose bleeds?

We are from Alaska and are currently visiting in West Texas(dry climate). We have been here 7 days, and for the past 4 days, my 15 year old has been having at least one nose bleed per day. I know that it's probably just due to the climate change, but wonder if and when I should start worrying and take him to a doctor. At first the nose bleeds were light and the blood was bright red, they are now there's quite a bit more blood and today it was very dark red. Does that mean anything? Is there anything I can do for him at home that will make them ease up or at least make him more comfortable. He's getting quite woozy and we have a week left here in Texas, any help would be much appreciated.