hi sorry about the delay, at present i think you need to work your upper core muscles lower traps, rhomboids serratus anterior these are the muscles you need to work mainly, once these are working correctly then you can look at your true neck muscles, but i do believe that by working on these you should find the neck pain goes.
try these for a while ( please remember I have not assessed you, and haven't taught you these face to face - any doubt don't do them and go and see a physio near you!!)
1) wall presses - hands on wall below shoulder hight, elbows slightly bent and relaxed. feet hip width apart and around 2 foot distances away. "Grow Tall" imagining a rod through your body and lean towards the wall as one ( not head or pelivs first). done correctly you should feel it between your shoulder blades, done incorrectly you'll feel it in the neck and arms. do x10 2-3 a day for a week and see the difference. let me know how you get on. regards physioroute