Cavalier behavioural issues

I have a 6 year old Cavalier.

He is not crate trained but has always been perfectly fine treating our house like his “crate”.

However, in the last year we have welcomed a new baby and moved house. He was on trazadone because of his stress with the new baby, but has been off it for six months and is perfectly fine around her.

He is now having what I would say is anxiety around separation and with strangers. If we go upstairs, he barks non stop. He won’t sleep downstairs and has to sleep in bed with us. If tradesmen come to our house he barks until he is exhausted and has tried to nip some.

This is all very out of character. Pre baby he was very calm and snoozy.

Given we have a baby, I think crate training at this age might be a bit too difficult.

Any suggestions?