It must be worrying her. Hopefully she doesn’t make things more inflammed.
There could be a variety of reasons for it. Simply some sediment in her pee that’s irritated tissue, urinary infection, bladder stone even. Insect bite. Swollen genitals can also be a sign of myxomatosis (if you live in region of the world where that is present) and can also be sign of rabbit syphillis bacterial infection,
Best have a vet look.{{{Nester}}}
I also think it would be worth seeking a couple other opinions for vets about spaying. Intact female rabbits have a high incidence of developing uterine cancer and other uterine infections as they age.
“If left entire, female rabbits run a big risk of developing cancer of the uterus in later life – a study in 2004 estimated a 50-80% chance in a rabbit over 3 years. Entire females can also develop mammary tumours, and can have phantom pregnancies. Their hormones can make them aggressive and hard to handle. They also obviously run the risk of pregnancy if there is any possibility of access to entire male rabbits (including relatives), and a female rabbit can get pregnant immediately after giving birth.” https://www.therabbitdoctors.com.au/copy-of-vaccinations