My dad is 69 and he quit smoking end of January, he's always been a heavy smoker for probably 50 years. The first two weeks he started to get smell and taste back and seemed fine, but after the first two weeks he started to get other symptoms such as insomnia, cough, mucus, fatigue (from the insomnia we believe) and shortness of breath. He is coming up to near 8 weeks now and still feels bad.

Now, my dad is not a worrier like me, especially when it comes to health, I am convinced it is something bad (I have not told that him that). First google search about quitting smoking says all these are normal things when quitting. But another search has suggest heart failure.

Does anyone have any advice, I have told him to go doctors but he is saying its just because of quitting smoking. But I worried its something more.