to think if someone is telling you they are uncomfortable

[risetowefall]

because they need the loo that they are desperate

If they are about ten or older I expect them to just go find a loo and no need to tell me.

Maybe not quite at the desperate point but no one likes discomfort.
What's the story ?
Is someone being kept from using the loo ?

Yes, I would suggest they need to be excused to go to the toilet (not that anyone should need to be excused for anything!)