Please help.

I’m wondering if someone has experienced anything like this with their kid and if so, what what the issue and diagnosis?

My son was born at 37weeks and smallish, more and more hes grown he has had some developmental issues. He currently has a sleep consultant(never slept well) , dietician(has allergies), paediatrician(growth issue, surgery due), development nurse all looking at different aspects of his little self.

My question is about speech and language and other developmental milestones going backwards.

For example: my son started off trying to talk and mimic after a year old etc, he was clearly able to say and mimic at least a few words. No frustration. As time went on he progressed started copying more words humming to the sounds of duas on tv etc. But then he started throwing tantrums started self harming and hitting his head a lot etc... we quickly figured out howto help him calm down and stop self harming and give him extra cuddles and different ways to approach this.

And now he doesn’t say any words nor does he try. He gets really frustrated if we even try sounds with him. He even stopped saying or being able to say his name and other things he had learned like mama, baba, baby, nom nom etc. He now just babbles. He will be two this month. He doesnt mimic. He gets violent if we even try.

Anyone had this type of regression? If so what helped or was there an actual medical issue?