Won't eat after spay

DO NOT GIVE MEDS ON AN EMPTY STOMACH!  She will have a very sensitive stomach right now and those meds can be very irritating.  Try adding warm water to the food, maybe sprinkle some cheese on it or something to make it appealing.  She shouldn't eat a full meal anyway, just about half.  Tomorrow she should be able to eat like normal.

I agree with Colliewog...anytime any of my animals have had any sort of anesthesia, they are only allowed a small meal if they will eat it at all.  Your pup is probably just feeling the affects of the anesthesia still.  If you have to, wait until the morning to give the pain pill.  I probably wouldn't handle her a lot though.  Cheese almost always works for my BT who doesn't always want to eat.  Even if you can get a little food in her tummy it will be better then trying to give it on an empty tummy. 
 
EDA: You said in another post that the vet said to give the pills once she eats.  I wonder if it would be OK to give it in the morning?  Also, when I had a really sick kitty last summer, I had to force feed her chicken or other meat flavored jarred baby food without anything else in it for a week to get her back to a healthy state.  If it is necessary that she take the meds tonight, would something sort of bland like that help entice her a little without making her sick???

Wait until she feels like eating even if that's overnight or even noon the next day. And adding warm water to the food is a good idea. Relax. She is probably still groggy, and the anesthesia kinda turns everything off. She'll be okay. She'll be VERY hungry once she's had time to rest.

My dogs never ate after they were spayed/neutered until very late the day after. I wouldn't give meds on an empty stomach though, ever. I was never given pain pills for the spay though, and this is a huge reason why.

Thanks for all the advice.  I ended up putting the pills in with her food and just left her food and water available to her all night in case she decided she wanted anything.  She is doing much better this morning!  She is starting to nibble at her food and drinking water now!  Thanks again!

BTW Welcome to the forum!!!!  We all want to see pics of your baby!!!