I have sort of a small parent/teacher social network set up for my school. I use my .htaccess file to make the links to teacher profiles cleaner and to add a trailing slash to all urls. I get this problem when going to /teachers/teacher-name/ the link (sometimes) redirects to /teachers/teacher-name.php.php.php.php.php.php.php.php... Below is my .htaccess file. Sometimes if I clear my browser cache in Chrome it temporarily fixes it. I can't exactly wright .htaccess syntax, but I'm pretty familiar with it. Any suggestions are appreciated!

RewriteEngine on
RewriteBase /

#remove php ext
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^([^/]+)/$ $1.php
RewriteRule ^([^/]+)/([^/]+)/$ $1/$2.php

#force trailing slash/
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteRule ^(.*)([^/])$    /$1$2/ [L,R=301]

#other rewrites
RewriteRule ^teachers/([^/\.]+)/$ /teachers/profile.php?u=$1
RewriteRule ^teachers/([^/\.]+)/posts/$ /teachers/posts.php?u=$1
RewriteRule ^teachers/([^/\.]+)/posts/([^/\.]+)/$ /teachers/post.php?u=$1&p=$2

RewriteRule ^gallery/([^/\.]+)/$ /gallery/album.php?n=$1
RewriteRule ^gallery/([^/\.]+)/slideshow/$ /gallery/slideshow.php?n=$1
RewriteRule ^gallery/([^/\.]+)/([^/\.]+)/([^/\.]+)/$ /gallery/photo.php?a=$1&p=$2&e=$3

EDIT:I have attached a screenshot of exactly what I'm talking about.