I was gonna say its sounds like a chest infection but im no doctor.
Hi, welcome to the forum. Your symptoms suggestive of respiratory in origin. Long term smoking will cause a interstitial lung disease. The causes for shortness of breath are Bronchospasm, Pulmonary embolism, Pneumothorax, Pulmonary infection - bronchitis, pneumonia.
The cause relevant in your case could be pneumonia or bronchitis. But, it is usually accompanied by fever, cough etc.
Feeling of something in throat or heart burn needs evaluation; the possible reason maybe acid reflux esp. laryngeal reflux. You need to consult a gastroenterologist and get evaluated the severity of the disease. Endoscopy will be helpful for the diagnosis and assessment of any esophageal damage.
You should stop taking spicy food, tea, coffee, alcohol and smoking which will exaggerate the condition.
I suggest you to consult a physician to rule out the respiratory cause. Blood tests and chest x-ray will help to aid the diagnosis. Take care and regards.
Are you Coughting anything up like flem? If you are what colour is it?