Severe Headaches

[gngr78us]

I have been experiencing headaches since my car accident in Nov08.  I have been through Chiropractic, Massage Physical Therapy, Pain Management and then PT again myofacial(sp) release.  Nothing seems to help.  The pain meds allow me to sleep but I wake up within two hours still with the horrible headache.  I also have been taking muscle relaxers, and still get the headaches.  The interesting thing is that if i dont take the muscle relaxers i can get a headache withing 6 hours.  When i am taking the muscle relaxers I still get them just not as often.   Xrays were normal, MRI of neck show slipped disc and spinal cord slightly rotated.  I got Facet shots, which made the neck pain go away but nothing will help the headaches.  The headaches start at the base of skull and work up to top of head they feel deep.  Most times it is so deep it feels like a worm tying to dig out of my head.  Light nor sounds bother me when I do have the headaches sneezing, bending over, and coughing make it worse.  I have been keeping a journal and the PM and GP doctors cant pinpoint anything.  I havent seen anyone else other than PT, GP and Chiro.  I see the doc tom, just wondering if you have any adice.
Thanks
Jennifer