Follow-up: it appears your Pinterest button uses another class than usual. This is why Easy FancyBox does not recognize it properly to avoid this conflict.
Could you try the following script snippet in a text widget or in your themes footer.php where it must come before/above the wp_footer() call!
<script type="text/javascript">
jQuery(document).on('ready post-load',
function(){ jQuery("a.pinterest").addClass("nofancybox"); }
);
</script>
Let me know how that works out 🙂