Brief Answer: It may be psoriatic spondylitis. Detailed Answer: Hello, Pain in the spine is not normal. Since you have a history of psoriatic arthritis, there is a possibility that it may be affecting your spine. If you have symptoms like pain more with inactivity and rest, better with exercise and pain worse at night associated with stiffness - these may be features of psoriatic spondylitis. However this may also be a mechanical type of back pain associated with strain on spine. So it is important to find out the cause of back pain as that will decide the treatment you need to undertake. Hope I have answered your question. Regards

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