You have undergone all tests and clinical examinations which still suggest nothing noticeably abnormal in your condition. What does this mean? It could mean you are worried - possibly you are well but worried. The reason seems simple - your smoking
. If that is the reason for your worries, you are definitely right as after some time end up having a sinister condition. Stop smoking completely and wait for couple of months to see if you have any improvement. The only other thing that you have to rule out is a acid reflux
disease which could mimic some of these symptoms. In addition to quitting smoking, take frequent small meals, avoid spicy food, avoid too much of tea and coffee, avoid stress
and keep a gap of two hours between your last meal and the time you go to bed.