Hello and thankyou for approaching DoctorSpring with your query. The cervical lymphnode that you have is nothing to worry, unless it increases in size, you notice more lymph node swellings, or its red or painful on touch. Your normal CBC reports, rule out any pathology. However do keep a watch on it to notice any changes. The important thing you need to keep in mind is that Lymph nodes are normal glands in the body. They are required for the proper functioning by fighting infection and inflammation. So it is normal for them to get enlarged, Unless thee is a suspicious pattern (which can be determined by your Doctor) there is no reason to worry . The sure way to know for real what the node is by doing a fine needle biopsy. This can be considered at a later stage if the node persists.
As for the breathing symptoms you are experiencing, will be due to the damage caused to your lungs by smoking. Smoke tends to damage the lung lining as a result of which you notice the sputum which has debris from your lung caused by the smoke. Cigarette smoking also tends to damage the airways and lungs resulting in inflammation which makes it narrows your airways and makes it difficult to breathe in and out. The above two are completely reversible on treatment and quitting smoking. Nicotine patches are found very effective as a therapy to quit smoking and is relatively safe. Few patients experience side effects and need to decrease the dosage accordingly. Avoid using the patch at night as it causes disturbed sleep and vivid dreams. The click on the throat, the sputum production all are non specific signs and you need not be worried about these
I suggest you visit the Medical center and get your 'Pulmonary Funtion Tests' (PFTs) if possible (in view of your long term smoking history). This will help diagnose any obstruction in your airways and can be treated accordingly.
It is really great know that you are exercising properly and taking good care of health. Please do continue this. Consider a Lymph Node biopsy if it persists. Quit smoking as soon as possible and you will be all set for great health.
Wishing you good health, and you can follow up with any further query.
Thankyou