Sorry to keep commenting, I keep remembering more stuff. I've also seen a physiotherapist. Is that similar to a physiatrist?

Thank you for responding. I have had a thorough exam with Dr.s who checked for facet joint pain(bend backwards & they twisted the shoulders rt. & left, bend forwards & twist, strength tested, etc.) said that the movements they had me do would present alot of pain if the problem was the facet joints. Thinks the cause is muscle weakness in the trunk(back) from a couple of things in  my past(won't go into whole story) Do you think the exam was thorough enough?

Forgot to mention I've also been working w/a chiropractor who's helped me tremendously with some pelvic (SI joint) instability & a physical therapist for strengthening.

Hi,
  The best thing is to see a physiatrist for a full examination (they have so many maneuvers to bring different pains out and  tell if its a soft tissue/muscle induced pain ..for general information about  back pains , please see my comment on April 14 for jaycop4
   Back to your questions
   wondering what the symptoms of facet joint problems are & how are they diagnosed?
    Depends on the location of the facet joints, meaning high cervical , low one or thoracic..or lumbar which may  give exactly your symptomes (localized stiffness)... for the 2nd part of the Qs ..generally Lumbar MRI is a non-invasive and allows for excellent visualization of the soft tissue and discs..but if (like your case) MRI is normal and your exam suggist a mechanical cause (a physical exam is crucial here) then Discography could show a distention of a facet joint .
Would an xray or MRI show it? X ray is used to diagnose fractures and evaluate the bony anatomy while there is something called "Dynamic lumbar spine films"  which is done by asking you to do flexion and extension of the back and take picture or X-ray views, this may demonstrate abnormal movement (subluxation).  About the MRI I already answered.

    God Bless
     Bob  Hilton