Custom excerpt messes up "next page" at bottom

I decided to change the way posts are displayed on the frontpage on my blog by pulling the featured image and custom excerpt from each post instead of styling every post and then using the <!–more–> tag. I wrote the following code and placed it in wrappers.php where the postcontent goes to pull the excerpt, whic is when the problem occured. The theme is made with artisteer.

<?php  if(is_single() || is_page()) {
	echo $content;
	} else {
	the_excerpt();
	echo '<a href="'. get_permalink($post->ID) . '"><img src="https://violentcinema.se/wp-content/themes/ViolentCinema3/images/read-more.jpg"></a>';
	}
?>