Hello and welcome to HCM.
History of 9 months of pain and
stiffness around neck may denote some degenerative spinal disc problems in neck area.
Probably exaggerated in your case due to your job because of sitting at one place for long time(as you have mentioned in query)
If I were your treating doctor,I would recommend,
-investigations like
X ray neck
-anti inflammatory drugs like
ibuprofen or
naproxen twice daily for couple of days
-warm compress over neck and back for 20 minutes ,3-4 times in a day
-do muscle relaxation exercises involving flexion,extension,rotation of neck and back
-if still pain persists,muscle relaxants like tablet
baclofen .
-Always sit with support to your neck and lower back area.Neck and upper back should be in straight line while sitting.Avoid sitting for long at one place.
Hope this information helps.
Thanks and regards.