Brief Answer:
?? Suspecting a spine related cause

Detailed Answer:
Hello sir and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. If the pain has occurred and persists without any apparent trauma (direct or indirect) like a whiplash injury, sports, fall, etc; it will require both a physical examination along with either an X-ray of the region or an MRI scan (more detailed) of the spine. Conditions like arthritis, disc herniation, etc; are common conditions for such a presentation.

But with the added symptom of a headache, I do also recommend a neurological consultation especially if you experienced any extra symptoms of a fever, nausea, vomiting, etc. An infection of the meninges of the brain presents in such a manner, but usually does not last for a month.

Inflammation (due to a few of the conditions listed above), injury, infection, etc; are of the broad categories we should consider and rule out/confirm. Please do try and schedule an appointment with your doctor for the same, and you can consider taking any pain management medication that seems to suit you and provide relief in the meantime.

I hope you find my response helpful. Please feel free to write back to me for any further clarifications. I am always here to help.

Best wishes.

---