Has she gone at all since the spay? If not, defn. call the vet asap, okay? If so, I'd still call and ask about it, bc it can be an issue that needs be addressed bc of the spay - you don't want her straining against those stitches. You might try giving some canned pumpkin - perhaps mix in a bit of oil and/or butter - *and* make her drink more water by taking a small bowl of water, add karo or honey to make it "sweet water" - so she'll hydrate.
As for bathing, you have to wait for now. You could use a baby wipe or something if you need to clean her up, gently.