Waking for a wee but nothing coming

[SuitablyMulled]

For the past 5 nights my 7yo DS has woken in the night needing a wee. He goes for a wee, one comes out and then immediately he feels he needs to go again and nothing comes out. Last night he did it before bed as well as in the night.

after the first night we got stricter about no drinks after 5:30 (this is the usual approach and he doesn’t usually need a night wee on this) as we’d got a bit slacker with timings. But he’s still doing it.

no other symptoms but thinking I should get him to the drs to rule out a UTI? Any experience of this?

Is he having an erection rather than needing a wee, but doesn’t know the difference?

What colour is his wee in the day or at night?

@SuitablyMulled , he needs more water, not less. And he needs a GP appointment to find out what's going on asap.