A rude awakening for all

This morning around 6 am, Banjo had another episode.  This time I was home too so I experienced a Banjo seizure (in full effect I might add).  Banjo got up and was having this weird thing with his stomach that made a lot of noise.  I had Neil take him into the bathroom so that if he threw up at least it would be easier to clean up than if it were on the carpet.  Then he quickly raced onto the bed squatted over me and started peeing.  A few seconds later he was growling and seizing.  The seizure lasted about 2 minutes, and then he was "dead"  for another few minutes, but then his tail started wagging and pretty soon he was back to life.  Afterwards our bed, and myself were soaked in dog urine and anal juices.  It was pretty scary and quite smelly.  Everyone got a bath this morning.  We are wondering if we've maybe nailed down what causes the seizures.  Yesterday Neil fed Banjo quite a few grapes, which apparently are really bad for dogs.  So we're hoping that if we eliminate those he'll be a happy go lucky non-epileptic dood again.