I had this with Leo about a month ago, and I was sure at the time it was him turning, he is head down now, so I am convinced that was what it was, he went nuts, was like he was having an epileptic fit of something, and it took my breath away it was so strong! Didn't feel like the hiccups I got with Jackson all the time which were a lot more subtle, like a bump every 5 seconds or so.