2yo male Exotic Shorthair dribbling urine

[jake42]

Hi,
this is Gus, a happy 2yo male well-loved indoor Exotic Shorthair. He's begun to dribble urine on a regular basis, perhaps 2 times a day (and possibly more). He's in very good form and plays well. His food/litter is the same as always. He eats only dry James Wellbeloved No Cereal dry food and plenty of water always. He uses his litter as before but if you pick him up he'll often leave a small 1inch dribble of wee.
We took him to the vet who gave antibiotics. That was 3 weeks ago and no improvement. He's still seemingly happy and gets lots of attention. Vet has no idea now. He was fussy when a kitten with his food and after much trials settled well on James Wellbeloved No Cereal 18 mths ago.
Any ideas very welcome,
Thanks,
J