I've been coughing up phlegm. ..Having a hard time breathing when inhaling...Pain on leftside, hurts worse when I lay down and pain also by shoulder?

See doctor. If you are having problems breathing, you need evaluation by your doctor or in the emergency room. If you have a cough with sputum production, and problems breathing, you could have a respiratory or lung infection. But you should be evaluated.
See doctor... Shortness of breath is a serious and sometimes life-threatening symptom so you need to be evaluated by a doctor asap! go to an er if you cannot be seen by your doctor today! you may have bronchospasm related to COPD or asthma. Your pain may be musculoskeletal from the coughing but this needs to be evaluated to be certain. Treatment depends on diagnosis. See a doctor today!