Thanks for the helpful reply. Interestingly, I started a new job in July 2014 which involved long hours using a computer and lots of driving. The symptom onset was within a few months of starting this job. I've been seeing an osteopath who said my symptoms are classic of someone who is sitting with a poor posture at a computer.

Probably should have mentioned that osteopathy has not made any difference and I'm about to start physiotherapy. Fingers crossed it will help me sleep!