Back pain may be due to various reasons (arthritis, disc prolapse, nerve compression, muscle spasm, fibromyalgia, to name a few). If your back pain is worse at night or early morning, or is associated with stiffness, then it may be due to Ankylosing Spondylitis (a type of arthritis)
Next Steps
If you have these symptoms, then consult a Rheumatologist for proper diagnosis and treatment