Thanks for writing in. I am qualified and certified cardiologist. In one line answer to your question yes it is possible to give infective endocarditis
prophylaxis given before getting a tattoo.
Nonetheless, this murmur can be entirely benign (say because of anemia
, thin buld with some turbulence across mitral or pulmonary valve
of no significance), therefore, I would suggest to you how about getting echocardiography
done. That will result in finding no disease and obviate the need for medication on the other you could be having bicuspid aortic with some aortic leak causing murmur. The later situation you would not need prophylaxix you will have to follow it up with the cardiologist later on.