Many people who train get shoulder injuries, it's part and parcel.
It's important that once you know something is wrong, you begin to address the issue using appropriate steps. Although I think this forum, and the advice in it, are very positive steps, one guy speculating over the internet isn't enough to diagnose injuries.
Here's some good links I found, which will help people with one of the most common types of injury: 'Shoulder impingement' get the issue dealt with at an early stage.
Link 1 shows some physiotherapy tests which differentiate between different issues which seem like impingement.
Link 2 gives good advice on how to be an intelligent patient, and ask doctor's the right questions, which will hopefully lead to better advice than "Rest, and ice it, FOREVER....."