What Causes Pain Below Rib While Taking Deep Breath Or Speaking?

I'm having a very sharp pain in my left side below my rib. Whenever I take a deep breath, move, or speak it feels like I'm being stabbed. Yesterday I went to the hospital because i was so bad that I couldn't handle it, but they sent me home because it was just constipation or a colonic spasm, as they put it. I just researched it, however, and the website I found says I should go back to the ER. What's your advice?