In most instances, the cause of middle back pain is strain. Many muscles in your middle back can become strained if you have poor posture, sit at a desk most of the day, or have tried to lift something too heavy or with improper lifting techniques. If you perform repetitive movements that affect your back, this can also be a cause of the pain.
There can be joint issues, too. A joint injury can occur from trauma, like after an accident, or from natural wear and tear over time. If you have a degenerative disease like arthritis, joint issues can also develop.
Another cause of middle back pain can be a problem with a vertebra. It can make your ribs hurt and can even make breathing painful. The treatment of middle back pain can be as simple as getting some rest, or it can involve medications and therapy.