hi, my ds does this. He was very prem and has mild cerbral palsy. I don't think that's connected but saying this just to be complete. He does it when he hurts himself which he does a lot as he falls a lot.
Anyway what do we do. First we try not to worry.
Second we are trained in baby cpr because he was prem. I have used it once when he was a few days old, not for breath holding but I know I do know what to do if I have to.
third blowing does nothing for DS, we tried it the nursery tried it, nothing
shouting sometimes works, as it gives DS a shock
as does tickling
as does ignoring him until he passes out and then comes back as instinct kicks in.
We were told it does then take time to come back to normal, he then gets clingy and odd, but sooner or later comes back
epilepsy has been ruled out.
He is now 24 months corrected and it is getting better
I am sure that this too will pass