Achilles tendon injury?

I was told by my local running store that I have a achilles tendon injury. It hurts more when I get up and walk or after sleeping when I get up and move around. Its not to bad if I am up and walking for awile just a lil sore. It also just not hurt when I am relaxing. I have been taking Ibroprofin and icing. How often do you recommend to ice and how often? I have a marathon in 3 weeks so we will see how this goes