I remember feeling those whilst pregnant with DD. My Obstetrician said that although it felt fit like that they probably weren't in reality, just normal movements that felt kind of odd due to positioning etc; he said it was quite common too. My DD is fine, she never really had anything I could attribute that sort of movement to once out in the world (doesn't move when asleep or anything) so who knows. It was pretty worrying though but I'm sure your bub is fine