Back muscle spasm. What should i do?

I do gym on regular basis .i think due to over excercise i am having back muscle spasm .its left lat. Its gets pumped too much if i do any excercise and i am having this from last 3-4 weeks. And i am not doing gym any more coz of this . I have checked this to ciroprector for twice but got no results . I just want to feel normal from my back (left lat + mid back) and wanna continue my excercise .my body type is ectomoprh so i got skinny way to soon if i not go to gym or not do any excercise. I am getting skinny again. Plz solve my back muscle spam. Or whatever this is. It happens coz of when i was doing chest excercise on incline bench and so far i know i extended my back too much.so i think i get hyper extension also. It give ache little while breathing as well. Tell me please what should i do??