nearly 5 yr old refusing to admit he needs a wee when he clearly does, and then insisting I go to the toilet with him...

[northerner]

And it is driving me mad. He shuffles and holds himself, I ask him many times if he needs a wee. He says no. Then suddenly with urgency he needs to go and insists I go with him.

I've tried everything to encourage him to go alone but he screams and crys.

WE don;t have a loo downstairs so he has to go upstairs, he also will not play alone in his room if I am downstairs.

What do you suggest?

Mine does this too - but usually wets himself too Drives me completely nuts, and the washing is a nightmare. He often wants me to go with him to the toilet at home too - no idea why (he's ok playing in his room though)
I'll be watching this with great interest

He is like this when you go out, or only at home?
I would just go with him for a while, TBH.
Maybe he's just going through a bit of a clingy phase, and I'm sure it will soon wear off if the whole thing is played down.
DS2 was like this for a while - didn't want to be out of my sight, and it was tiring but didn't last long.
Another thing we did was have a radio playing on the landing, so he didn't feel alone when he went upstairs.