it looks to me that you are having symptoms of cervical spondylitis
. i would suggest you to take following steps.
1.Avoid using very high pillow or a very soft mattress
2. Take tablet Pregabalin
and Methylcobalamine daiy
3.Apply hot water fomentation and Diclofenec ointment at neck
4.Visit a physiotherapist and start neck muscle strengthening exercises
5.Myoril or Myospaz are muscle relaxant
if pain and tightness is very severeMRI
needed if symptoms persist after these steps.
I can assure you that it is not fatal.