Sharp pain hard to breathe when i went to pick up 2 gallon milk. it was sudden. lasted 2 minutes.can this be a back injury or a muscle injury already had? feel as if kick in my side where my lungs and side are my right side between ribcage and hip.

Yes, possibly: Good morning, Yes, this could possibly be due to a back injury or muscle injury, but it could be what we call pleurisy, which happens when the lung essentially gets stuck to the ribcage, making it painful to take a deep breath in. Most of the time, this is "self-limiting" or goes away on its own but if you find it happens more frequently or happens with physical activity, let your PCP know.