Severe middle back pain when taking a deep breath?

Just as I said above I suddenly got severe back pain when I breath in. Hot showers make it feel sorta better, finals just ended and I have a bit of a cold from stress. But what strikes me is that I've experienced this pain once before a couple weeks ago. Then on another day I had the chills and bluish skin also a couple weeks ago. Should I go to the ER or wait out until morning?