Male cat - cystitis -advice ?

[PotOfTulips]

We have a young male neutered cat who has now had 2 bouts of cystitis - one in July and one now in mid September.
He seems otherwise healthy and happy, full of energy, likes interacting with us, and able to jump around. He enjoys going outside in the day, we keep him in overnight.

The vet can't find any obvious cause, e.g. no crystals in urine or infection in urine, so has suggested it might be due to stress. We aren't convinced by this as he does seem overall very content and happy at home.

Has anyone had a similar experience and if so, what did you change (if anything) to improve things for the cat ?
Also did you find that any food seemed to help (e.g. Royal Canin "calm" or urinary cat food? )

Adding pic for cat tax - he is next to one of his favourite toys, a box with holes scooped out where we can hide treats etc.

We had something similar about 18 months ago. There were no obvious stress triggers (although he is generally quite anxious - unlike his sister who is the ultimate example of "not a single fuck was given" 😂).

I started mixing a bit of water into his wet food to make sure he was getting enough fluids (initially it was just while he was having his meds but i kept it up).

No idea if it made a difference but he's been ok since (touch wood), despite being a total wuss!

And he's gorgeous!

I gave mine Cystease and removed all dry from his diet.

Is your gorgeous boy the only pet in the house, Op? Or any young kids who could be stressing him? Neighbourhood cats?
My dcat is ten and very fat and has had a few urinary issues over the last couple of years.
He seems to be better since ddog died in the new year so I suspect stress was a major part of it.
He is also on urinary food, mostly wet but with a bit of dry at night. I do sometimes add water to his food as a pp suggested, and he also likes to drink the milk from the bottom of my cornflakes bowl (I know milk doesn’t suit some cats but mine has never had a problem).
He has a capsule of cystaid mixed into his food once a day, which is about £13 for a month’s supply. I get it from Amazon.
You could also try Feliway if he is stressed.
Has the vet said he is overweight? If so, losing a bit might help. Easier said than done, I know (glares at fat cat waiting for yet another meal) despite already having had breakfast and lunch.
You might need to try a few urinary foods to see which he likes best. Mine is currently on Almo Nature, Smilla and Concept for Life. We tried Hills before but he didn’t seem as keen on those. You’ll need to order online. I’m using zooplus at the moment as they usually have offers on.

Thank you all. I think I will try gradually changing his diet. I've ordered some "urinary" stuff as well as Royal Canin "Calm".
Cystease or cystaid also look good to try. I'm also going to try more liquid overall, I bought some little tins of Canagan soup and the fish version was sucked up straight away.

He is the only cat in the house and he really seems to have life just the way he wants it, no other obvious stressors at all. I wonder if it's just that he has a tendency to this, rather like humans who have a tendency to IBS.

At present the vet advises to keep him in the house for a few days and it's clear he'd like to be outside. Normally he loves being out in the garden and coming to investigate anything we are doing.