You need to move root /usr/share/nginx/html; outside of the location block so that it applies to all URLs, not just ones ending with .php. I’d also recommend adding try_files $uri =404; as a security measure in order to prevent people from trying to execute non-php files (e.g. user uploads).

server {
    listen  80;
    server_name newsfeedapps.com www.newsfeedapps.com;

    root           /usr/share/nginx/html;

    location / {
        try_files $uri $uri/ /index.php?$args;
    }

    error_page  500 502 503 504  /50x.html;
    location ~ \.php$ {
            try_files $uri =404;
            fastcgi_pass   127.0.0.1:9000;
            fastcgi_index  index.php;
            fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
            include        fastcgi_params;
        }
}

Make sure you restart nginx so that the changes take effect:

sudo service nginx restart