Your high cortisol levels might well be due to the pain, so you might not be able to lower them properly until you get your pain under control.
That said, can you do any form of exercise? Exercise can be very helpful in lowering stress hormone levels, even if it's only for a couple of hours. You may want to your doctors about the best kinds of exercise for your condition, though.
How about a hot bath or a visit to the sauna? A relaxation technique, perhaps? Stress management, so that stressors from the outside don't aggravate the problem? Anything that helps to combat stress might help lower your cortisol levels as well.
Valerian doesn't do anything for me, either. My pharmacist said that it has a paradoxical effect on some people, making them wide awake instead of sleepy. I take hops instead when I need something to help me sleep.
All the best!!