Why is my Christmas Tree going brown

Hi All,    I planted a christmas tree in the border of my garden  approx 3 years ago,  it had been growing lovely with no problem that is until about  2 weeks ago, i noticed that the tree started to turn brown all over. I was surprised at how quickly this happened but  now it has started to grow new shoots at the tips of the branches.  I am confused as to what is happening with christmas tree. Is there anything i can do to save the christmas tree or is the beginging of the end. 

I would really appreciate some help and advice.  Thank you..x