In the index page on mydomain.com that creates the frame, put some PHP in there.
Instead of this:
<frameset>
<frame src="http://myuniversity.com/mylocation">
</frameset>
Do this:
<frameset>
<frame src="http://myuniversity.com/mylocation/index.php?source=<?php echo $_HTTP_REFERER"; ?>">
</frameset>
Then, your University page will be passed the HTTP_REFERER and you can find out the referrer by looking at $_REQUEST['source'];