Sudden upper back pain since july. the pain is severe. what is it?

Nerve impingement: can be caused by nerve being sandwiched between two spinal bones, pressed by a bulging disc. It can cause muscle spasm, back pain and burning pain. This condition must be professionally managed. See an interventional pain management specialist for definitive diagnosis and management.

Most commonly: The most common cause of acute (new) back pain without numbness, weakness, or pain shooting down an arm or leg would be a muscular strain. These can be severe, and complete recovery often takes 6 weeks. Sometimes medications (i.e. ibuprofen or naproxen), physical therapy, or imaging are indicated, but a primary care visit (Family or Internal Medicine) is the first place to go.