What is this sharp pain when I'm inhaling?

Occasionally when I breathe in I get a very bad , sharp pain in my lower chest/back. This does not happen all the time and it tends to come and go weeks or months in between happening , strange or what. I inhale and feel this pain and half way through my inhale I have to stop , this helps the pain go away temporarily then I continue my inhale and the pain can be there or not , if it is not there I continue with taking in the breath , if its there I have to exhale .I am a healthy , active and fit 31 year old male.