Hello, I think your father's problem is better to go to the hospital for examination. Old people will have many diseases when they are older. If they feel a little unwell, they should be examined as soon as possible, have a general examination, determine what the reason is, and then prescribe the right medicine. During the period, you can eat some drugs or fruits that moisten your throat and clear your lungs, relieve cough and resolve phlegm. You should see a doctor as soon as possible.