I'm fourteen and I'm not sure what the clump of blood is. If you get nosebleeds because of allergies (me), try going to a sink and let the blood drip into that. Turn on the cold water and wipe away the blood. Cold water will slow it down after a while. It may take a few minutes for it to slow down. After it starts to slow down from the water, try and breathe through your nose. Try and get some water in the nostril to clear away the blood. Don't inhale the water. If you feel something in your nose, blow just enough to get it out. When it stops, keep using the cold water to clear your nose of blood. The nostril should then be clear and you should be able to breathe through it. Then get something with calcium and drink or eat it whatever it is you chose.
Follow these instructions in this order and it might possibly work. I believe some people have sensitive nostrils. If you are one of those people, I don't recommend it to you but if you are willing to try it then go ahead.