Rabbits always need pain medication following any surgery, especially a female rabbit that has just been spayed. It would be the equivalent of not giving pain meds to a woman that has just had a hysterectomy.
https://rabbit.org/the-importance-of-analgesia-pain-control-for-pet-rabbits/
https://rabbitwelfare.co.uk/rabbit-health/medical/pain-management-rabbits/
A vet that says a rabbit doesn't need pain meds after a spay is not an experienced rabbit vet. I would strongly urge not going back to that vet again, besides to pick up the needed pain medication for your rabbit as soon as you can possibly get it. Usually it will be meloxicam, dosed at around 1mg/kg per day(dose may be divided into twice daily dosing), which will be about 0.6ml twice a day for a 4lb rabbit or 1.2ml once a day, of the 1.5mg/ml suspension. You should be given enough for 3-5 days.
If the vet prescribes the dog dose(0.1-0.2mg/kg) which is much less than the recommended rabbit dose, which vets inexperienced with rabbits commonly do, I would suggest showing your vet the article on the dose recommended for rabbits(0.3-0.6mg/kg twice a day).
https://www.vgr1.com/metacam/
If you don't want your rabbit to wait until morning for the necessary pain relief, if your vet has an emergency contact, phone that or find an emergency vet clinic with a vet experienced with rabbits to take your rabbit to tonight.
https://rabbit.org/veterinarians/
If your vet does have an emergency contact, I would say that your rabbit is grinding her teeth in pain and needs the pain medication you had requested earlier. You should only be charged for the medication and not an additional office visit charge. If they try to charge an additional emergency visit charge, I personally would refuse to pay it and make a formal complaint to the manager of the office.
Like Watermelons mentioned, if your rabbit isn't eating on her own by morning, which it's doubtful she will be because she's in pain, in addition to the pain medication, she will also need to be syringe fed every 4 hours until she starts eating well on her own. The vet should provide a syringe feeding mix(usually Oxbow Critical Care), or in a pinch a feeding mush can be made from soaking the rabbits food pellets in warm water(made up fresh each time).
https://wabbitwiki.com/wiki/Medicating_your_rabbit
https://rabbitwelfare.co.uk/rabbit-health/medical/syringe-feeding-guide/
https://rabbit.org/care/after-surgery/
https://wabbitwiki.com/wiki/Spaying_and_neutering_rabbits
Rabbits can become hypothermic after surgery, so it's important to make sure their body temp is normal, or if chilled(if the ears are cold) a rabbit needs to be warmed up safely using rabbit safe warm packs, also making sure your rabbit doesn't get too hot.
If in doubt of the needed medication or the care needed for your rabbit, it's best to contact an emergency vet clinic with a knowledgeable rabbit vet tonight if at all possible.
