Please post your /etc/php5/fpm/pool.d/www.conf and /etc/nginx/sites-enabled/default config files.

Here are my config files:

/etc/php5/fpm/pool.d/www.conf

[www]

user = www-data
group = www-data
listen = /var/run/php5-fpm.sock
listen.owner = www-data
listen.group = www-data

pm = dynamic
pm.maxchildren = 5
pm.startservers = 2
pm.minspareservers = 1
pm.maxspareservers = 3
chdir = /

/etc/nginx/sites-enabled/default

server {
listen 80 defaultserver;
listen [::]:80 defaultserver ipv6only=on;

    root /var/www/default;
    index index.php index.html index.htm;

    # Make site accessible from http://localhost/
    server_name mydomainhere.com;
    error_log /var/www/default/error.log;

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

    # pass the PHP scripts to FastCGI server listening on /var/run/php5-fpm.sock
    location ~ \.php$ {
            try_files $uri /index.php =404;
            fastcgi_pass unix:/var/run/php5-fpm.sock;
            fastcgi_index index.php;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
            include fastcgi_params;
    }
}