Use this to create the html for the slider:

function jma_nivo($input = array() ){
	$defaults = array(
		'class' => '',
		'acf_field' => 'gallery',
		'image_size' => 'tb_grid',
		'thumb_size' => 'tb_thumb',
		'post_id' => '',
		'image_ids' => '',
	);
	foreach($defaults as $var => $default){
		$args[$var] = isset($input[$var]) && $input[$var]? $input[$var]: $default;
	}
	extract($args);
	if(!$post_id){
		global $post;
		$post_id = $post->ID;
	}
	$return = '';
	if($image_ids || $acf_field){
		$return = '<div class="jma-port-slider">';
		$return .= '<div class="jma_nivo ' . $class . ' metaslider metaslider-nivo ml-slider" style="overflow: hidden">';
		if($image_ids)
			$image_ids = explode(',', $image_ids);
		else
			$image_ids = get_field($acf_field, $post_id, false);
		if($image_ids){
			foreach($image_ids as $image_id){
				$image_attributes = wp_get_attachment_image_src( $image_id, $image_size );
				$thumb_attributes = wp_get_attachment_image_src( $image_id, $thumb_size );
				if($image_attributes)
					$return .= '<img src="' . $image_attributes[0] . '" data-thumb="' . $thumb_attributes[0] . '" />';
			}
		}
		$return .= '</div><!--jma-nivo--></div>';	
	
	}
	return $return;
}

then this for shortcode (notice you can add the params to the shortcode directly).
image ids will over-write gallery id and show the images directly:

function nivo_slider($atts){
	ob_start();    
	$x = '';
	extract( shortcode_atts( array(
		'class' => '',
		'acf_field' => 'gallery',
		'image_size' => 'tb_grid',
		'thumb_size' => 'tb_thumb',
		'post_id' => '',
		'image_ids' => '',
		), $atts ) );
	echo jma_nivo(array(
		'class'=> $class,
		'acf_field'=> $acf_field,
		'image_size'=> $image_size,
		'thumb_size' => $thumb_size,
		'post_id'=> $post_id,
		'image_ids' => $image_ids,
		));
	$x = ob_get_contents();
	ob_end_clean();
	return str_replace("\r\n", '', $x);
}
add_shortcode('nivo_slider','nivo_slider');

or this to add to content:

function jma_nivo_slider_content($content){
	$new = jma_nivo(array('class'=> 'new'));
	return  $content  . $new;
}
function jma_site_filters_hooks(){
	if(is_singular('portfolio_item') ){
		add_filter('the_content', 'jma_nivo_slider_content');
	}
}
add_action('template_redirect', 'jma_site_filters_hooks');

and this to add the files for nivo slider (http://www.jqueryscript.net/slider/nivo-slider.html)

function jma_nivo_files() {
	    wp_enqueue_style( 'include_nivo_css', plugins_url('/nivo-slider.css', __FILE__) );
	    wp_enqueue_script( 'include_nivo_js', plugins_url('/jquery.nivo.slider.js', __FILE__), array( 'jquery' ) );
	    wp_enqueue_script( 'jma_nivo_js', plugins_url('/jma_meta_js.js', __FILE__), array( 'jquery', 'include_nivo_js' ) );
}
add_action( 'wp_enqueue_scripts', 'jma_nivo_files' );

and include in the plugin root a file called jma_meta_js.js and populate it with this code:

jQuery(document).ready(function($){
	$(window).load(function() {
		
		$('.jma_nivo').each(function() {
			$(this).nivoSlider({
				effect: 'random',
				animSpeed: 500,
				pauseTime: 3000,
				controlNav: false,
				prevText: '',
				nextText: '',
				//controlNavThumbs: true,
	
			});
		});
	});
});