Hi. My Question Is, Every Time I Bend Over To

Hi. my question is, every time I bend over to wash my face or brush my teeth, or even bend over while taking notes during class, when I sit up straight, my sternum gets a tight feeling pain. almost like It needs to be popped. I used to be able to push on it and pop it, but now it won't pop any more. I just want to know what you think could be causing this type of tightness right in my sternum.