PHP Link in Wordpress Menu - Won't Add

I have the following link in my code:

<a title='Submit a new article' href='<?php echo bp_loggedin_user_domain();?>articles/new-article/' />New Article</a>

This links to:

It allows me to write a new article on the website and submit it pending review.

I would like to add it to my Wordpress Menu, however I am required to add a normal URL and I have no idea what to enter. I can't put the URL it links to, as it is related to my particular username.

Any ideas?