The action described sounds like a sacrificial rite, specifically a priest performing a ritual blood sacrifice. Such rituals took place in a number of ancient religions, from the Jewish Yahwist tradition to the Mayan human sacrifices. Other details of the dream may provide more information as to its specific meaning.
The taste of blood in this dream is a powerful metaphor representing your feelings of guilt and responsibility.
In this dream, the blood could represent your health. Carrying the blood in the bag might suggest that you are taking chances with your health.
It mean you had a bad dream.
It could mean something in the real world knowing you need to finally step away from that something.
Dreams about blood can have many different meanings depending on other elements in the dream. Similarly, dreaming of one's niece could mean many different things depending on what the niece is doing in the dream. A basic principle in understanding dreams is that the dream is about the dreamer, not about other persons that appear in the dream. So the blood and the niece in this dream reflect something about the dreamer's feelings, memories or experiences.
You will lose something minor/major. (an object, person, friend or etc...)
The dream illustrates conflicted feelings of wanting both to get rid of something nasty at the same time one hesitates to get rid of it completely.
it means you are having a nightmare and nothing else.
This dream suggests feeling as if someone is trying to cast blame on the dreamer. It reflects the expression of having "blood on one's hands."
you watch too many movies
Some thing is very wrong; seek professional medical advice quickly.
Dream interpretation is subjective and can vary based on personal experiences and beliefs. However, throwing away old clothes in a dream could symbolize letting go of past experiences or emotions that are no longer serving you. It may suggest a desire for renewal, change, or decluttering in your waking life. Consider the specific details and emotions in the dream for a more accurate interpretation.