Run AJAX req with no conflict ?

Hello,
I have a function in functions.php file that makes json request. This is how I am calling this function:

define('IS_AJAX_REQUEST', isset($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest');
if (IS_AJAX_REQUEST){
  loadmore();
}

Above code works just fine, but the problem is it conflicts with other AJAX request, for example, I see error message saying cannot execute loadmore() when I try to upload an image.

I tried following but none worked.

if (IS_AJAX_REQUEST && is_page()){
  loadmore();
}

if (is_page())
if (IS_AJAX_REQUEST){
  loadmore();
}
}

if (IS_AJAX_REQUEST){
 if (is_page()) loadmore();  }
}

I only wanna execute loadmore() function when viewing a page. How can I do that ?