What's wrong with my rabbit?

[Truffle Risotto]

Hello, I have two 5 month old indoor free roam French Lop brothers that are both neutered and have been for almost 3 months, they are also both litter trained, however last weekend they started marking their territory again, I researched about this and read that it's pretty normal, but what is concerning me is one of my rabbits is dribbling pee and his bum and tail area is very wet. This has happened before to my other rabbit a few weeks after the neuter and we took him back to the vet and she checked him and found nothing wrong and said he is probably just marking, soon after the check up he was fine again, he just stopped dribbling pee and getting his tail wet; so I'm confused why the other brother is doing this now as he has never done this before, it has been a few days and we are going to call the vet tomorrow but this time a different one, I hope maybe they will know what's wrong, if it really is just marking territory? But his tail still gets wet even when he pees in his litter box. I also researched about a UTI in rabbits but he doesn't really have much of the symptoms listed, he's acting like how he usually acts and eats and drinks the same, doesn't show any signs of pain when he pees, the colour of his pee is normal. So I just don't what's wrong but I'm worried about him because I know how harmful it is for rabbits to get pee on their fur and skin, I hope maybe someone can tell me what's wrong. Thank you so much.

 

[JBun]

If his tail and bum are getting wet due to dribbling urine and not from spraying pee to mark, then likely causes are UTI or bladder calcium build up. E. cuniculi can also sometimes cause urinary incontinence.
http://www.bio.miami.edu/hare/urinary.html
http://wildpro.twycrosszoo.org/S/00dis/Miscellaneous/UrinaryIncontinenceRabbit.htm

Until you get to the vet you will need to keep a very close eye on him and check his bum several times a day to make sure he doesn't get fly strike. If you have any flies in the house I would get rid of them as much as possible to prevent it from occurring.

 

[John Wick]

Does the rabbit go through the entire tail-arch motion when peeing? Sort of like this: https://www.instagram.com/p/Bz-vhBtolqS/ ... so you see at the end of the clip, the tail is not as curled up as it was at the beginning of the clip. Typically this curl-up motion prevents them from peeing on themselves.

If one brother had it and now the other is showing symptoms, it'd be important to consider common factors between them, such as their environment cleanliness and diet. As @JBun mentions, EC is also something that can cause urinary symptoms.

 

[Truffle Risotto]

@JBun thank you, yes I'm always checking up on him and we have nets on the windows so there is no flies. The vets here don't specialise in rabbits and the closest one is far away, if the vet here doesn't know what it is, is it possible to treat it ourselves?

@John Wick yes, he does go through the entire tail-arch when peeing. His brother had this more than 2 months ago and it just went away after about a week. So right now he is the only one that has this problem and they both eat the same things and the same amount, the environment they're in is very clean too as they're free roam and I clean everyday and spot clean throughout the day