Got dull aching pain on left side in middle of my back. sharp pain comes when take deep breaths or cough.

More info needed: Your brief description is nonspecific. There are several possibilities ranging from rare to common. The most common cause in a young adult is likely to be related to a strain in the ribcage or back area. The fact that the pain occurs with a cough or deep breath indicates it may be related to movement of the diaphragm, ribs, muscles, etc. If symptoms do not improve see your Dr.

Muscle spasm/strain: Hi, it seems you have a muscle strain= pulled muscle, you need to take Ibuprofen, decrease the activities which make it worse, try some stretch exercises, use Ice/Heat pack, if not better see your MD.