Look at my comments in code. If this doesnt work. Please make a fiddle so we can understand the problem better
$('.accordion-header').click(function () {
if($(this).is('.inactive-header')) {
// I think this line is the one thats toggling everything and closing
//all the open ones so try commenting it out
//$('.active-header').toggleClass('active-header').toggleClass('inactive-header').next().slideToggle().toggleClass('open-content');
$(this).toggleClass('active-header').toggleClass('inactive-header');
$(this).next().slideToggle().toggleClass('open-content');
}
else {
$(this).toggleClass('active-header').toggleClass('inactive-header');
$(this).next().slideToggle().toggleClass('open-content');
}
});