Thanks for the plugin i ll try that out too but i found the solution to my problem. I used a couple of if/else if to display the menus on certain categories.
<?php
if(has_nav_menu('primary'))
{
if(is_category(example)){
$locationMenu=menuname }
?>
<?php
wp_nav_menu( array(
'menu' => $locationMenu,
'theme_location'=> 'primary',
'container' => false,
'menu_id' => 'nav',
'fallback_cb' => 'wp_page_menu'
) );
} else {
?>
If the category doesnt change the menu won’t change, even if you click on a post in that category!I am putting it here so others can search it too!