Difficulty speaking. The most common cause of "difficulty speaking" is shortness of breath. This is usually a sign of serious illness including pneumonia, blood clot to lung, heart attack, asthma, heart failure, or other severe allergic reaction. You should see a doctor promptly for shortness of breath. Fatigue is a separate problem. Most people can cope with it if it is short-term; after 2 months, see a doctor.
Diclofenac and cough. It depends on the reason why he prescribed that. At first pass I would say no, its not ok and that you should get him to re-visit this. But it might be for another obscure reason. Please go back and question him thanks.