Baby boy has developed a head twitch?! Advice

My 13 month old has started twitching his head the last week. He puts his chin down and sort of flicks his head to one side a few times. I’m so worried about him, he’s fine apart from that and it only lasts a couple of second and it happens 2/3 times a day but does anyone have any experience or advice with this?? We’ve been switching down to one nap the last few weeks and he does get tired so could this have brought it on?? He had a big bump to the head before Xmas but dr wasn’t worried about it. Apart from that he’s met all his milestones in good time. I’m not sure wether to take him to our dr or not.