When i inhale the left side of my upper back hurts, it's only when i breathe deeply, or sneeze. it's been going on for 2 days. please help. ?

Several thoughts: Pain in the upper back only when taking a deep breath suggests a muscle strain. If you get similar pain in the same area on doing muscular maneuvers such as raising your shoulder, twisting and bending it supports the diagnosis of a muscle strain. If the pain persists you should see your physician in case the cause is more serious than muscle strain.