Stinky butt issue

So my puppy turns 8 months today and the past two months we started to realized out of no where her butt stunk. Like bad. The whole room smelt and we would gag. We gave her a bath and that usually works but sometimes dosent which usually means she needed her anal gland expression. Other times the bath work it still baffled me because cause I was giving her one bath a week due to the smell. She’s cut short right now and didn’t really have this issue until right before her first real haircut when we thanked god this all happened right before her groom. Not it’s like every 3-4 days and her butt starts to STINK. And everything it touches smells to and has to be washed or cleaned. We have taken Her to get her anal glands expressed and this time they said nothing came out. She eats a good food for her and I put salmon oil and probiotics in it. I really don’t know what the issue is. Has anyone experienced this? It’s honestly getting gross and more work for myself as I have to keep baithing her. There isn’t any poop on her or anything either. She’s is stubborn and does sometimes hold in her poop because she’d rather play outside then go poo and I wonder if this is causing the issue? Any suggestions please bc this stench is honestly gag worthy