Welcome to healthcare magic!
You are having the problem because you are not accustomed to a static posture of the neck, it takes some time to get adjusted to the static posture.
Wear it continuously in the hours of activity and you would get used to this in 7-10 days.
Meanwhile you can take Tab. Ultracet
to ease your problems.
You can take it off at showers but avoid shaking the head, maintain the neck steady as if you are having a collar there.
You can also take it off when going to bed.
I hope this advise would be helpful for you.
Still if you have any queries or doubts, please write me back,
I would be happy to solve them.
Wish you a great health!