Nginx 502 Bad Gateway only when wordpress is requested

Hi

I am sure it is a stupid mistake but I am trying to get a wordpress running after installing php-pfm.
My test info.php file works like a charm and nginx serves it without a problem (see https://wordpress3-635639788058487716.cloudapp.net/info.php) but when requesting my wordpress file (which was working perfectly before the install) it serves me with a 502 Bad Gateway Error.

Here is my default.conf

server {
    listen      80 default;
    server_name _;
    root        /var/www/vhosts/default;
    index       index.html index.htm;
    charset     utf-8;

    access_log  /var/log/nginx/default.access.log  main;
    error_log   /var/log/nginx/default.error.log;

    include     /etc/nginx/drop;

    rewrite /wp-admin$ $scheme://$host$uri/ permanent;
    #rewrite ^(.*)(index|home|default)\.html? $1 permanent;

    set $mobile '';
    #include /etc/nginx/mobile-detect;

     location ~* ^/wp-(content|admin|includes) {
         index   index.php index.html index.htm;
        try_files $uri =404;
        fastcgi_pass unix:/tmp/php5-fpm.sock;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
         if ($request_filename ~ .*\.php) {
#             break;
#             proxy_pass https://backend;
         }
         include /etc/nginx/expires;
    }

    location ~ \.php$ {
        root           /var/www/vhosts/default;
        try_files $uri =404;
#        fastcgi_pass   127.0.0.1:9000;
        fastcgi_pass unix:/tmp/php5-fpm.sock;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }

    #location ~* \.(js|css|html?|xml|gz|jpe?g|gif|png|swf|wmv|flv|ico)$ {
    #    index   index.html index.htm;
    #    include /etc/nginx/expires;
    #}

    location / {
        if ($request_filename ~ .*\.php) {
            break;
            proxy_pass https://backend;
        }
        include /etc/nginx/expires;

        set $do_not_cache 0;
        if ($http_cookie ~* "comment_author_|wordpress_(?!test_cookie)|wp-postpass_" ) {
            set $do_not_cache 1;
        }
        if ($request_method = POST) {
            set $do_not_cache 1;
        }
        proxy_no_cache     $do_not_cache;
        proxy_cache_bypass $do_not_cache;

        proxy_redirect     off;
        proxy_cache        czone;
        proxy_cache_key    "$scheme://$host$request_uri$mobile";
        proxy_cache_valid  200 0m;
        proxy_pass https://backend;
    }

    #include     /etc/nginx/phpmyadmin;
    location ~* /(phpmyadmin|myadmin|pma) {
        access_log off;
        log_not_found off;
        return 404;
    }

    # redirect server error pages to the static page /50x.html
    #
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

and my nginx.conf

user  nginx;
worker_processes  4;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;

events {
    worker_connections  1024;
    use epoll;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format main    '$remote_addr - $remote_user [$time_local] "$request" '
                       '$status $body_bytes_sent "$http_referer" '
                       '"$http_user_agent" "$http_x_forwarded_for"';
    log_format backend '$http_x_forwarded_for - $remote_user [$time_local] "$request" '
                       '$status $body_bytes_sent "$http_referer" '
                       '"$http_user_agent"';

    access_log  /var/log/nginx/access.log  main;

    server_name_in_redirect off;
    server_tokens      off;

    sendfile           on;
    tcp_nopush         off;

    keepalive_timeout  5;

    client_max_body_size    1200m;
    client_body_buffer_size 256k;

    if_modified_since before;

    fastcgi_buffer_size 64k;
    fastcgi_buffers 4 64k;

    gzip              on;
    gzip_http_version 1.0;
    gzip_vary         on;
    gzip_comp_level   6;
    gzip_types        text/plain
                      text/xml
                      text/css
                      text/javascript
                      application/xhtml+xml
                      application/xml
                      application/rss+xml
                      application/atom_xml
                      application/javascript
                      application/x-javascript
                      application/x-httpd-php;
    gzip_disable      "MSIE [1-6]\.";

    proxy_cache_path  /var/cache/nginx/proxy_cache levels=1:2
                      keys_zone=czone:32m max_size=256m inactive=1440m;
    proxy_temp_path   /var/cache/nginx/proxy_temp;
    proxy_cache_key   "$scheme://$host$request_uri";
    proxy_set_header  Host               $host;
    proxy_set_header  X-Real-IP          $remote_addr;
    proxy_set_header  Remote-Addr        $remote_addr;
    proxy_set_header  X-Forwarded-Host   $host;
    proxy_set_header  X-Forwarded-Server $host;
    proxy_set_header  X-Forwarded-For    $proxy_add_x_forwarded_for;
    proxy_set_header  Accept-Encoding    "";
    proxy_hide_header X-Pingback;
    proxy_hide_header Link;
    proxy_hide_header ETag;
    proxy_connect_timeout 5;
    proxy_send_timeout 10;
    proxy_read_timeout 120;
    proxy_cache_use_stale timeout invalid_header http_500 http_502 http_503 http_504;
    proxy_cache_lock on;
    proxy_cache_lock_timeout 5s;

    upstream backend {
        server unix:/var/run/nginx-backend.sock;
    }

    upstream phpfpm {
        server unix:/var/run/php-fpm.sock;
    }

    include /etc/nginx/conf.d/*.conf;
}

Thank you so much for your help.