Strange freeze moments

[AliceWunder]

I don't know how to explain it but sometimes my 12 y/o son makes a strange expression before he's about to say something or reply to us. For a second or 2 his eyes will have an empty look and he does an empty expression almost like in a movie when someone enters your body. I know it sounds weird and in the beginning we were joking about it that what is this you're doing? Are you copying one of your friends? ...we thought he's doing it intentionally but when we make him aware of it he says he doesn't realise he's doing it. We even called it brain freeze.
Now came the point that it's happening daily and I'm starting to worry cuz I have no clue what this behaviour is and what's causing it. This morning for example he walked into the kitchen and before he could greet me he had this freeze look again and I looked in his face and gently asked him if he's ok. He said that he could feel it a bit, the fact that this happened to him. I'm trying not to make him too much aware of it since by now I truly believe he's doing it unconsciously.
Should I ask a doctor? And how so I explain this to the doc? I can't recreate or film it since I don't know the triggers. Initially I thought when he's stressed or under pressure that could cause it but like this morning it was an ordinary situation.

I think you have described it very well and a doctor would understand what you mean. I’d be very concerned about it and would assume he’s having seizures or something neurological is happening, I would go to the doctor asap. Have you heard of petit mal seizures?

Please google absence seizures, my step son had them which eventually led to full tonic clonic seizures. If you can try and video it neurologist will ask you to do this anyway, we could never get a video as it was over so quickly. Please see a Dr asap. My stepson was diagnosed with epilepsy and had medication which controlled them completely.

No I never heard of it, but omg when I just looked it up, that's exactly the expression he does

You need to go to the doctor about this. My friend had this and was diagnosed with epilepsy, which she is able to control very well with medication.

My first thought was seizures too. My friend had the ones you write about.

I spotted this happening in a child a few years ago. I reported it to parents, who thankfully took it seriously and took him to the doctor. He was eventually treated for a type of epilepsy. He's now doing a lot better and doesn't need medication, so don't fret too much, but get it looked at asap.

I’m a GP and I also think this could be absence seizures. Though could be lots of other possibilities. Definitely see the GP about it.

Thank you all, appreciate your help. Will definitely see a GP