Brief Answer:
Intercostal neuritis

Detailed Answer:
Hi,

Thank you for posting the question.
I have gone through your medical history in detail.

Having pinched nerves in the chest is rare.The kind of pain that you are presently experiencing in the chest might be due to intercostal neuritis (inflammation of the nerves that lie between two adjacent ribs) or due to chest muscle strain.

Have you lifted anything heavy recently?
Do you think that this chest pain has started as a result of sleeping in an awkward position?

Pinched nerves are seen more commonly in neck or lower back region and is quite uncommon in chest region.

I would suggest you to take methylcobalamin,folic acid and vitamin B12 tablets with anti inflammatory tablets like ibuprofen,paracetamol or tramadol.
Addition of muscle relaxants like thiocolchicoside,tizanidine will help.

Wear a supporting corset around the chest and apply local analgesic gel followed by hot fomentation.

I hope the answer was useful.

Feel free to ask me any follow up queries that you may have.

Thank you.
Kind regards.

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Brief Answer:
tendinitis

Detailed Answer:
Hi,
Such cracking sounds are usually caused by tendinitis (an inflammed tendon slipping over the adjacent muscle). This condition is usually benign and does not cause any harm in long run unless it becomes painful.

Muscles in lower back can be sore due to local inflammation or pinched nerves in lower back.An MRI of the back will help to confirm the exact reason.

Thanks

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