Brief Answer:
Can be due to various causes.

Detailed Answer:
Hello,
Thanks for posting your query.
A pain in the back only in the morning could be due to-
1. A beat-up mattress that does not give adequate support might cause stiffness and pain. You need to use a firm mattress preferably a cotton mattress which gives our back a good support.
2. Low oxygen levels in muscles while lying down- frequent change in postures or lying on your side might provide the relief.
3. Disc herniation or spinal canal stenosis- Can be diagnosed after investigations like MRI.
4. Arthritis or ankylosing spondylosis.
5. Weak core muscles-Strengthening the muscles that support the spine helps keep the spine in its proper position and reduce risk of sprains, strains and lower back pain. Maintain fitness with exercises that include back stretching and strengthening exercises under guidance of a physiotherapist.
If you will not feel better after following above suggestions then a detailed examination by an orthopedician will help in detecting the exact cause. The treatment further depends on the cause.
I hope this answers your query.
In case you have additional questions or doubts, you can forward them to me, and I shall be glad to help you out.
Wishing you good health
Regards
Dr. Praveen Tayal
For future query, you can directly approach me through my profile URL http://bit.ly/Dr-Praveen-Tayal

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Brief Answer:
Can be related to posture.

Detailed Answer:
Hello,

Thanks for writing again.

The pain only on the left side can be related to posture or a disc prolapse or a renal calculus. MRI scan of the back and a direct examination will help in detecting the exact cause.

Hope my answer is helpful.

Do accept my answer in case there are no further queries.

Regards.

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