Hello First of all I want to tell you that water pill is not able to get rid of fluid in lungs. Now you mentioned that there is fluid in the lungs ( means both ) and pneumonia ( left side ) . There is pain in the left shoulder as well as pain in the same arm . Whenever there is pleurisy , it causes pain in the concerned joint due to irritation over diaphragm ( of the concerned side). As you also mentioned that there is weakness as well as no energy . All these symptoms may be due to , these reasons , these includes. 1 Tuberculosis as this is the most common cause of pleural effusion ( pleurisy ) . Diagnosis can be confirmed by X ray chest as well as blood examination for C B C, E S R , sputum for AF B. When such patient visit in my clinic I at once advise for drain of fluid from lung ( as in your case left side ) . Advised for culture and sensitivity examination of drained ( aspirated ) fluid. Usually tuberculosis is the main cause but some times cancer may be the cause of such pleurisy ( rarely ) , as if blood present in aspirated fluid , we suspect as cancer . Shortness of breath, lack of energy , pain in shoulder, pain in lung all are due to pleural effusion. So consult another physician and get his opinion as early as possible.