How often does a ficial heart murmur heal itself and can a leaking heart valve close itself? Also he hasn't seen cardiologist since diagnosed @ 15mo

Uncertain terms. I don't know what the word "ficial" means. Most children who have a heart murmur have a "normal" murmur. That means that there is noise with blood flow, but no actual underlying abnormality causing the noise. This is a normal finding, and typically, with growth, the murmur disappears. Other terms that people use are "innocent" and "functional" to describe such murmurs.