I have had nothing but problems with my two females and their butts after the groomer. Most groomers do express the glands but not the right way, it's best for a vet to do it. If she wasn't trimmed, ask what kind of comb they used . If they brushed her out to hard they could have irritated her skin. Move her fur to see if skin is irritated.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD