Moose, my little Jack Russell/Chihuahua mix, has something odd wrong with him. The first time he did this was a few months ago. He was lying down napping and then jumped up whining and howling like he was in awful pain. He came running to me for help with his tail between his legs. He didn't do it again until day before yesterday and now he has done it twice. There is nothing obviously wrong with him and the episodes only last a few minutes, then he goes back to being himself. What do you think could be wrong with my Moose??