You work in a public swimming pool setting and had an initial kidney infection (I assume that was treated) which may have shut down your urine production leading to your not passing urine during the infection.
I gather you drink alcohol (or have until recently). What sorts of maximum consumption have occurred? What sort of largest total amount consumed for a month or a year, has occurred? [I'm trying to get a sense of the magnitude of the alcohol impact, if it's a quantity thing.] Very clearly, at present any alcohol consumption is potentially extremely dangerous (and I don't know why but that's an obvious enough point here).
You've been tested undoubtedly many times for protein (creatine?) in your urine (correct?). It's presence would indicate possible major kidney function / damage problems.
If your kidneys are o.k. (as also seen by you're not experiencing major bloating symptoms irregularly), it may be something to do with your bladder and urethra, and the muscles controlling those. What imaging tests have already been done? Have you had (VERY risky) a kidney biopsy done?
I suspect, you've some esoteric kidney infection that's slipping under the radar and has been suppressed to the point of not being easily detected, or, the kidney infection has majorly damaged your kidneys (yet, the classic way of detecting damaged kidneys is protein in urine and I gather that's not being seen). I'm guessing the infection has led to your kidneys just shutting down, but then you'd be experiencing bloating (you're not, right?).
You've had a 24 hour total volume of urine test, right?
I think the physio's needed, if only because it just might help / resolve the problem (probably won't but definitely ought to be tried on the off chance).
The initial kidney infection was treated yes, and as for alcohol consumption I wasn't 21 whilst living in America so wasn't able to drink for 6 months anyway, it's only been since coming home (I was never a big drinker anyway I'd go out twice a month an have 2/3 drinks an be sick/dodgy stomach/nauseous) - so for the past 3 months I've not touched alcohol at all.
When I don't pass much water I do tend to bloat up an get regular pains in my lower back when this occurs.
I have had tons of water tests done, flow test, ultrasounds on my kindey an bladder, urodynamics test.
I've had to keep diarys of my diet & how much water I pass/ fluids I drink to show the doctors, an there last comment was that I need to train my bladder (they suggest going the toilet every 15 mins to see if I could pass anything but this didn't seem to help me).
Shall be starting the physio soon so will see if that helps anything then
Thank you for your advice