These complaints can be due to a combination of causes which you have mentioned of low
Vitamin D levels and a sitting desk job which itself can cause strain in and around the muscles of your neck, if the working environment or your sitting posture is not appropriate.
From your end you can start with correcting your posture while working, taking adequate rest in between woorking, and supplement yourself with CAPSULE OR SACHET UPRISE D3 60k IU weekly once, probably every Sunday, for six week, which will correct the defecincy symptoms, followed by maintenance, continue with it one capsule or sachet every month for 6 Months.
If the pain from neck or shoulder is radiating to the arm or there is tingling or shock like senstaion, go for T. NEUROKIND G / T. PREGABA M 75 every night after food for 5 days.
For severe muscle pain if present, T. ZERODOL TH4 two times a day for 5 to 7 days, along with T. PANTAOP 40 mg in morning one tablet 30 mins before food for same Duration of using T. ZERODOL TH4.
Additionally you can take T. ZINCOVIT 1 tablet any time of day after food for 3 months, preferably not at time of taking T.PANTOP 40 mg, will help In correcting symptoms of other Vitamin and mineral deficiencies.
Next Steps
If symptoms do not improve, you there is aggrevated complaints, any episodes of dizziness or fainting, onset of new symptoms, consult an orthopedician or general physician/ practioner locally in an early clinic or hospital, to evaluate for any other cause.
You can connect with me on practo or via call/ WhatsApp (915093049 eight)