I am experiencing cough (worsened by: lying flat) (quality: no phlegm or mucus) , chest pain or discomfort (quality: feels sharp or stabbing, sens...

Cough: You don't need medical care for the average cough or sore throat. You often just need to give your body time to recover. Most are caused by viruses, which antibiotics can’t treat http://symptoms.webmd.com/cold-flu-map/treating-your-cough

Cough: Cough + chest pain may need to consider the possibility of a chest infection. Like Dr Pool says most are due to viral illnesses and will disappear with time however would be important to have a doctor examine and consider other causes such as reflux asthma or pneumonia depending on how you present. This should be done urgently if any breathing difficulties.

See pulmonologist: There are many causes of cough, few that can cause chest pain. If you are having shortness of breath with it, I would be worried about a pulmonary embolus. Could also be cardiac related especially since it gets worse with lying flat. Potentially could be asthma (based on symptoms you describe). Best bet is to be seen.