Screaming at every minor inconvenience

Hi guys, I have a 3 year old who is in speech therapy and on a waitlist for OT. No ABA here.

He is semi-verbal and a gestalt language processor. His receptive and expressive language is delayed.

He has recently started screaming (loud high-pitched screams all day long at home and outside followed by verbal stimming) at every minor inconvenience instead of using words he could use and also throws things high in the air in anger. He is frustrated all day. I tell him not to scream all day, he stops in that moment but does it again. I have tried everything distraction, redirection, taking toys away. Nothing works.

- Someone touches his toy ---> Scream

- Someone does not hand over something immediately ---> Scream

- Told no---> Scream

- Asked to wait ---> Scream

- Want something ---> Scream

- Asks me to say non-sensical words and sounds like "say Pay pay" "say ba ba" "say bopo" and if I say No, I'm not saying that ----> Scream

Is this sensory related or behaviour related?

Asking in this group because I do not have access to OT or BT where I live.