What Causes Throat Pain While Walking?

Hi Doctor,my dad is 70 years old.He is 5ft 7inchs.He is suffering from pain in throat while walking.Though he is having this problem since last 18 years or so but since last 2/3 years it has become severe.He has left smoking about 7 years back after about 40 years of smoking. He is not suffering from diabetes and never had any chest pain or heart attack ever.Few months back doctor suggested TMT test where he could run for little more than 2 minutes.Doc suggested angiography and prescribed Deplatta 75,Winitro 2.6,Liponorm 10mg.to be taken daily.Though this has given relief from pain while walking,he was diagonosed for high blood pressure for the first time a few days back.Could u please give some suggestion what is the exact ailment since he doesnt suffer from Chest pain and had no bp problem before taking the above medicines