General anxiety about lung cancer

Not sure whether this should be in the lung cancer section or the anxiety section or addiction section.

I am 42 years old and a secret social smoker (ie my friends i go out and drink with know I smoke, my wife and colleagues don't). Through my twenties I was a regular pack a day smoker but I'm meant to have given up.
I am constantly worried I have got Lung cancer. It distracts me from my work. I beat myself up when ever I smoke but still do it next time I have a couple of drinks.
I have a constant pain in my lower left side just under my ribs .... is this just some kind of neurotic thing? It started as an occasional pain.

I worry that by worrying I will cause and give myself the disease that scares me so much.

I keep on giving up smoking and am otherwise very healthy, I am very frustrated and scared. I have seen hypnotherapists on 3 occasions, used patches etc but my smoking happens when I have had a couple and nothing seems to stop me from doing it. I am otherwise very very disciplined.

Scared, embarrassed and frustrated