A sudden nosebleed is read as stress spilling over, or energy draining away under pressure. Bleeding in front of others is usually taken as embarrassment, or a fear that your strain is showing. A nosebleed that will not stop points to a situation that keeps costing you more than you planned. Dream books also link it to pride being hurt, or to being pushed too hard by someone. Folk tradition treats it as a sign to slow down rather than as anything about the body.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.