I am a teenager and I have a heart murmur where a little blood comes in when it pumps out could this go away?

Diagnosis? You don't provide enough information to give you any advice. Revisit with the diagnosing physician and ask for a specific diagnosis. Some murmurs are important and some murmurs are trivial.
Heart murmur. A heart murmur is a sound heard when listening to the heart. It can be caused by many things including a valve problem or a hole in the heart. It was also just be an innocent murmur with no cause. Whatever causes the murmur determines if it will go away. If you don't know why you have a murmur you can ask your doctor. You may be sent to a heart specialist for more testing. .