Thanks all. Jennie is at the specialists now in solihull. She was totally not herself, and even tried to bite the neurologist!!
She's checked in for yet another ultrasound, a full spine MRI and possibly a spinal fluid tap. The specialist is unsure if it is back - her symptoms are very episodic, she isn't in constant high levels of pain (well it certainly spikes higher).. she walks totally normally and doesn't display the back arching as Sheryl and Jennyspin have described their girls doing.
It is possible that she's got pain higher up the spine (shoulders to head), meningitis is a possibility but she doesn't necessarily have all the symptoms for that either.
THe specialist was supposed to call about 11am and hasn't - I'm never sure if that is good or bad...