Teen keeps making up lies about attempted suicide

[HeyUpDuckie]

My ds15 has autism, adhd and a learning disability hes in a sen school and lately keeps making up horrific things about trying to kill himself and self harming.

The thing is the ways hes saying hes doing things isn't true. The school do not believe him either as its just not possible the way hes describing. He also says cat scratches which i know is a cat scratch is him self harming himself.

Is this normal in asd teens? He keeps doing things like this and it comes out of nowhere. School have trained staff and said they do not believe for a second thats it true
He has a good life, good friends, hobbies etc were all baffled why he is lying.

Could he be copying the words of somebody else at school who is self-harming? Maybe he sees them getting additional support/attention or time out of the classroom and is hoping to be treated in the same way. I suspect it would be tricky for the school to tell you that but maybe it's something you could explore with him? Mimicry is definitely a feature of ASD hence my wondering if it's a copying behaviour. If not at school, could it be something he's seeing online?