JQuery :: Custom Form Validator - Adding Span After Input

I am working with customised form validator..I've this html structure
<div id="tab-perfil"><fieldset>
<legend>Dados Pessoais</legend>
<div class="columns">
<div class="colx3-left-double required">
<label for="nome">Nome</label>
<span class="relative">
<input type="text" name="nome" id="nome" value="" class="full-width">
</span></div>

What I want to do is after the input add a span, I know how to do that, just use insertAfter('#nome'); but I have a class for the ERROR and a class for the OK. This is what I have so far
this.find("#formulario_criar-cliente").submit(function(){
var $inputs = $('#formulario_criar-cliente div .required :input');
$inputs.each(function() {
if ($(this).val() == "") {
$(this).addClass("error");
} else {
$(this).removeClass("error");
}});
return false;
});

When I add the class error I want to show a span with a class="check-error" and when I remove the class I want to show a span with a class="check-ok" but remove the error one. This is for multiple inputs... and I don't know how to achieve that =x