6yr olds frequent need to wee!

[gilsteadmum]

My 6 year old daughter has been frequently needing a wee for the past couple of weeks. We have sent 2 urine samples off to be tested and both have come back clear of infection. The Dr has prescribed antibiotics 'just in case' but says that anything odd would have been picked up by the tests.
She visits the toilet anything between every 5 mins and every hour, seemingly depending on how much she's conscious of it / if she's nervous etc. and gets really distressed if she can't get to a toilet as soon as she needs to.
She says it doesn't hurt she 'just needs to wee'. It's started to get in the way of daily life as we're constantly looking for toilets and try to avoid long journeys.
Does anyone know exactly what they look for in a urine test and have you any ideas what could be wrong with her? We've considered cystitus, thrush and even diabeties but not sure if it is just a terrible nervous habit that's become a real problem.
Any advice would be welcome.

what happens if you don't let her go to the toilet or there simply isn't one around? I know you say she gets distressed but is she capable of holding her bladder or do accidents happen?

The longest she's gone without 'a visit' recently is an hour and a half (whilst we attempted a boat trip on holiday). She did manage to hold it but looked extremely uncomfortable and was really distressed by the time we found a toilet!
She's just finished her course of antibiotics today and seems a little better. We've been praising her for taking the foulest tasting medicine ever and commenting on how much better she seems in the hope that, if it is just habit, it might help her get over it.

Presumably she is managing to hold it at night?

Is she actually having a wee when she goes to the loo every 5 minutes?

Have you heard of a website called ERIC? They have a hlepline, I think. Perhaps they could help.