If it's not helping you, I would stop taking it and see if it's okay for you to go the "natural" route w/melatonin or valerian root. Melatonin worked really well for me for the sleeplessness associated with withdrawal. Just be sure you take that about 1/2 hour before bedtime and take only in a darkened room - even the light from a TV or computer screen can mess with the effectiveness of this supplement.
Sleep is one of the last things to return to normal after you quit. I know how frustrating it is so just try to rest as much as possible. Even if you're not sleeping, the downtime is still beneficial to your body.
do you have a high tolerance to muscle relaxers ? It may take some time ( in terms of hours ) to kick in but people usually say that it works well...