So yesterday I lifted and all I did was BOR's, Chins, and Face pulls. Nothing to strenuous. About halfway through my chins though I went for a drink at the water fountain and noticed that when I breathed in deeply my middle/left back hurt pretty bad. I hoped it would get better over time, but it is now evening of the next day and my mid/left back, up to my neck, hurts, especially when I turn my torso certain ways(especially when I turn to the left). Anyways, I have a 2nd degree BB test in TKD on thursday so I am going to take tomorrow off, then do my test the best I can, then take a couple days break and see how it goes. Any ideas of what I could have done? Is it just likely a pulled/irritated muscle?