My little one is 14 months and a few days ago he started doing this occasional twitch/jerky/spasm movement.
He's never done anything like it before, but he kind of jerks just for a second (kind of like if someone makes you jump), and does a small 'arghhh' sound at the same time. The first time he did it probably 6 or 7 times in a row. Then that evening he did it again but only a few times and more spaced out.
The next day nothing and then today this evening over dinner he did it again about 4 or 5 times in a row in his high chair.
Sometimes he smiles whilst doing it and it's not affected his mood or appetite or anything he's his usual happy self! He's walking/running around everywhere like normal!
Got a phone call with the GP tomorrow to ask, but wanted to get views?
He's teething as well at the moment so not sure if that's relevant!