Mechanical Low Back Pain: This is the most common cause of low back pain, especially when it is aggravated by sitting for too long. Prolonged sitting can put strain on the muscles and joints of the lower back, leading to pain.

Lumbar Disc Herniation: Herniated discs can cause low back pain that worsens with sitting, as sitting increases the intradiscal pressure. This condition can also lead to radiculopathy if the herniated disc compresses a nerve root.
Lumbar Muscle Strain: Overstretching or tearing of the muscles in the lower back can occur from sudden movement or overuse, leading to pain that may be exacerbated by prolonged sitting.
Degenerative Disc Disease: Although more common in older populations, degenerative disc disease can start early and cause low back pain, especially with activities that increase spinal stress, like sitting.

Cauda Equina Syndrome: A serious condition that occurs when the nerves in the spinal canal are compressed, leading to symptoms such as severe low back pain, sciatica, numbness, and weakness in the legs, as well as bladder and bowel dysfunction. It is a medical emergency requiring immediate attention.
Spinal Infection (e.g., Osteomyelitis, Discitis): Infections of the spine can cause severe back pain and are more likely in individuals with certain risk factors (e.g., recent surgery, intravenous drug use). These conditions require prompt diagnosis and treatment to prevent serious complications.
Spinal Tumor: Although rare, tumors in the spine can cause back pain, and it's crucial to consider this possibility, especially if there are "red flag" symptoms such as unexplained weight loss, fever, or a history of cancer.

Spondylolisthesis: A condition where one of the vertebrae slips forward over the bone below it, which can cause low back pain, especially with activities that increase lumbar lordosis, like sitting.
Sacroiliitis: Inflammation of the sacroiliac joints, which can be caused by various conditions, including inflammatory arthritis. It may cause low back pain and buttock pain.
Osteoporotic Compression Fracture: Although more common in older individuals with osteoporosis, younger individuals with risk factors (e.g., long-term steroid use, certain medical conditions) can also experience compression fractures, leading to sudden onset of back pain.