Stress Cystitis Caused By Going Outside

[ItsSnowJokes]

So our Kitten is now 8 months old, all vaccinations done, been spayed etc..... and 1.5 weeks ago we started letting her outside, supervised for about 20 minutes at a time. On Monday night she started the symptoms of stress cystitis (blood in urine, trying to go for a wee a lot of times and only a drop coming out). Tuesday trip to the vets and she has anti inflammatory medicine and also a bladder supplement to help it settle.

Vet said to slowly introduce outside again so yesterday we did 10 minutes again supervised and today 10 minutes. After lunch today she has started going back in her litter tray a lot, only a very small amount of wee coming out but no blood etc..... she is desperate to be let outside, anytime we open the door to the garden she is there trying to get out, she is still nervous of the garden, and crouches low when the wind blows.

I have never had this happen with my numerous cats before, is she going to have to be an indoor cat even though she is desperate to go out?

Bump incase anyone can help.

You might have a neighbourhood bully who's marked the garden as his territory, or going out on her own may just be a bit scary.
My girl is 11 and still only ventures halfway down the garden on the warmest days.
Maybe try again as it gets warmer & the weather is less blustery?
Also - does she have a cat flap to be able to bolt back indoors if worried (& is she confident using it?).

@AwkwardPaws27 we don't have a cat flap yet, we are awaiting it to be fitted (needs a while new glass panel and it's taking a long time!) But we always keep the door open so she can come back in when she wants and we have always been in the garden with her. She has never been out alone.