I'm 20 years old and have been experiencing a popping feeling under my right breast while taking a moderate-deep breath. The pop is very localized and is a little painful. The symptoms I notice seem to last anywhere from 10-30 minutes and then seem to go away on it's own. But I seem to have a couple episodes a day. I noticed it tends to happen mainly when I am sitting. It lingers a small ache in my chest after the episode is over and it's been going on for about a month. I don't know what it is or if I should feel alarmed by it. Has anyone else experienced this or know what might cause something like what I am experiencing?