You feel dizzy, weak, or faint. Your bleeding begins by going down the back of the throat rather than through the nose, even when you are sitting up or standing. You have lots of bruises not from injuries, or if you bruise easily. You have just started taking new medicine. When your nasal membranes dry out, they may feel itchy.
Some kids end up picking their noses as a way to relieve that itchy feeling.
This isn't a good idea. Use only enough to cover half the cotton bit of the swab. If you use more than that you'll end up with jelly globs up your nose and that can be uncomfortable. Very carefully insert the swab into the nostril and gently apply jelly on center wall of nose. Never insert the swab further than the cotton tip.