Though your body might not be showing any signs of damage, sometimes these are not necessary to conclude that you have been a little too rough with it. Even though you might not see a cut or a bruise, on the inside your body is feeling abused. This is why you are dreaming of a bloody nose, it is the only way for your body to warn you that you have been mistreating yourself. Have you been doing too much smoking or drinking lately? Have you been doing worse drugs than that? Have you been participating in dangerous and unnecessary sports challenges? These might all be reasons that you dream that you have a bloody nose.
If you dream that you have a bloody nose it can also be because you feel like you have a case of whiplash in real life. This is not to refer to a literal case of whiplash, but more of a metaphorical kind. You have just gone through a major change, and your mind needs a bit more time to catch up to your surroundings and everything that is going on in the wake of these massive changes. You are not quite ready to cope with the different changes that have been going on so this is how you react because of that. Because bloody noses usually happen because of an increase in altitude, this would suggest that you are feeling this way as the result of a pleasant change. Something good has happened which is causing you to react in this way. You cannot entirely handle the change because it’s happened so fast.
If you have a dream in which your nose is bleeding, this might be because you have been taking things a little too far recently or flying a bit too far off the handle. Have you had any confrontations where something relatively small was done wrong, but you blew up over it. Maybe someone gave you something you liked, and you blew a gasket thanking them. This type of dream would suggest that your erratic behavior that you have been exhibiting lately is detrimental to everything that you are working for and will eventually cause you to ruin yourself.
A bloody nose basically means in all of these interpretations that you have gone through some sort of change recently. A change in surroundings in one case, a change in behavior in another and a change in the level of physical abuse that you inflict on yourself in the third one. But the thing that all of them have in common is change. Be ready for a bloody nose in your dreams if you keep participating in activities that bring you to trying new things and experimenting.