I have just made this on a rush but would you please try this :
<?php
if( is_tag() ){
$tag = single_tag_title('', false);
}else{
$tag='';
}
if( is_category() ){
$cat = single_cat_title('', false);
}else{
$cat="";
}
$args = array(
'post_type' => 'post',
'post_status' => 'publish',
'tag' => $tag,
'posts_per_page' => $ppp,
'category_name' => $cat,
'offset' => $offset,
);
?>