i have a 3 year old chesapeake bay retriever. a few days ago he was laying on the floor and out of nowhere jolted up and ran into the other room, almost as if he had been shocked. since then it has happened a few other times. it appears that whatever it is it is causing a sharp jolt of pain or discomfort. from what i have observed it tends to happen more at night. any input would be greatly appreciate. thank you.