What causes middle back pain only on the left side that feels like a tight muscle being stretched out? what can i do to ease the pain?

Many possibilities: Many times the cause of middle back pain is referred from another body part or organ such as stomach, lung, or kidney. If caused by a back or spine problem, would initially treat with first aid measures such as ice , over-the-counter pain remedies, etc. If symptoms persist or associated with other symptoms, you should your physician.

Probable Rib: Ribs normally move up & down with breathing & are quite flexible to allow rotation & side-bending of the trunk.Unfortunately, sometimes either the muscles between ribs get spasmed or a rib, itself, can get locked up.Best way to ease the pain:see an osteopathic manipulative medicine dr.After a good history & phys incl hands-on osteopathic exam, he may be able to manipulate & fix affected area.