I hear lub-swish-dub only when laying on my stomach. the clinical nurse doesn't listen in this position and she told me to get tested for health anxiety. is it possible to hear a heart murmur only in certain positions?

Yes: It is certainly possible to have a murmur that changes with position; an innocent pediatric murmur often will change with position. You may want to have a second opinion.

Murmurs can be: Positional. Especially flow murmurs. An echocardiogram may be indicated for further evaluation.

Yes,: Several cardiac auscultation maneuvers make quiet murmurs louder or bring out intermittent ones. One is kneeling on hands & knees (pts think you are kidding or nuts...Until you find the murmur.) i forget which valve sound that enhances, but someone here will tag on that I am sure. Prone is same basic position, just harder to get stethescope under. (rn=2-4yrs, cardiology=4+3+2or3yrs). See cardiol.