Your doctor is absolutely right. Although there are chances of relapse, it is unlikely if you follow a good regimen of drugs, exercise and diet.
The chest tightness you feel occurs due to involvement of the lung parenchyma, and it will persist for a while. The symptoms of chest tightness will reduce over time.
My recommendations are as follows-
1) Complete the course of antibiotics prescribed. Do not neglect any future lung infection, however minor you may think it is, as there is a slight chance of relapse.
2) As you haven't mentioned if it was bacterial or viral pneumonia, I would recommend you to wean of the Adavir and use only the other inhaler which helps improve the breathing. On the other hand, if you suffered viral pneumonia, continue using ADAVIR.
3) Follow a good routine of exercise .Start with minor exercises and walking and slowly increase the degree of exercise.
4) It is very important that you stop smoking and consumption of alcohol.
5) Remember to take the yearly flu shots as your lungs are very susceptible now and are prone for infections.