What neurological conditions are common in pit bulls?

My 20-month-old male pitbull is displaying strange symptoms - obvious pain (though petting is liked), stiff hips (he now walks like a penguin), lethargy, and it seems like he's suffering mild, not-extra-pain-producing seizures (facial ticks, hyperventilation, "REMing" of the eyes). Any suggestions of what the condition may be? The vet has been of no help whatsoever, and blood tests are inconclusive.