Even if it doesn't show it could still be an abscess brewing...Does heat help? Could it be something that a chiro could try to adjust? Not making light of it but all of the surgeries, illness etc sometimes we neglect to consider the simple stuff, like maybe we could use an adjustment?
I slipped and fell 4yrs ago doing a flying splits (not as poetic as it sounds) and landed hard. Nothing broke so I got ignored but my sacral pain just kept getting worse til I could barely walk. X-rays showed nothing. They just kept upping the pain meds (I had a veritable pharmacy in my house because I refused to take them...I couldn't work on Tramadol and codeine killed my output)... I was at whit's end. Nearly suicidal...the pressure and pain just kept getting worse. Work was unbearable.
One day I met an Ethiopathe (sort of a cross between a chiro and an osteopath)...the first adjustment sounded like a car crash. Even he was scared. But the pain and pressure just went 'poof' and disappeared. I had a blocked nerve and he managed to unblock it...2 yrs of hell for nothing.
When traditional medicine does not find answers for me, especially concerning pain, I go elsewhere. But always make sure that I have a licensed and respectable specialist and not a quack.
Sharon