Sudden stammer and behaviour change

[Palmtree9]

Hi,
Just wondering if anyone else has experienced this. I have ready made contact with gp and waiting for an appt. My DS, who will be 3 in July, has suddenly over the last 6 weeks developed a stammer so bad that he can sometimes barely get a word out. He's also now only speaking in 1 word sentences (yes, no, that) and is having almighty meltdowns. Up until now, his speech has always been far ahead of where it would be expected to be.

I know the terrible 2s happen, but the tantrums coupled with being practically non verbal all of a sudden...does that seem like something else?

Does he go anywhere for childcare?
I’d be worrying that something was distressing him for such a sudden change to be happening.

He goes to a childminder in the week. It's so strange because cognitively and physically he's still ahead of where you'd expect him to be for his age. He's having some scans this morning at the hospital