This may be your anxiety and you may still need something to help with that. Talk to your doctor about all of this and go from there. Best wishes.
What mg xanax were you taking? And how many times a day? Stopping xanax without tapering can absolutely cause insomnia, but I'm not sure after a week if it could be entirely blamed on the xanax withdrawal. I ended up having to go cold turkey from 1.5mg of xanax a day and I stayed up for 3 nights straight. It was awful but I eventually fell asleep around 6am after the third night. Benadryl helped me and it also helped take the edge off of my anxiety. Xanax shouldn't be stopped cold turkey due to serious side effects of withdrawal but I don't think that after a week of use the withdrawals would be very severe, but I guess it depends on the dosage. I suggest calling your doc and letting them know what's going on. They may want you to start the xanax again and come off of it more slowly. But for the time being benadryl may help and try lying down watching a movie or listening to music to keep your mind occupied so its not racing and worrying about falling asleep. That may help as well.
Try theanine its a natural supplement or valerian root its supposed to help with sleeping problems they are natural supplements. If not then you really should go see a doctor because not sleeping is not good at all, they may give you ativan. Hope this helps.