Hi Doctor My Grand Father Age Is 73 .he Is

Hi Doctor my Grand father age is 73 .he is heart pasand..last 20 years he is talking tablet.now last 15days he has nee pain.our heart passant doctor told that in future if any problem comes in leg don't go to any hospital ,come to see me.as the doctor told we went to see the doctor yesterday but doctor is out of station..duty doctor is there we explain about that pain he discuss with chief doctor and they gave this tablet fenlong.he told that have it 5days morning and evening and come back to meet chief doctor after 7days.my Grand pa asked doctor what's the problem..he replied that take the tablet and come back we will say.i want to know that what's the problem and if any side effects are there taking this tablet..?please reply me doctor..?