I think you are aiming for something that binds the stool rather than a laxative that will cause contractions, but I cannot specifically comment on those products to know their action. I would try to get the advised product to be on the safe side though.
I had a young pullet earlier this year and she was impacted for at least 10 days before I got it cleared (I ended up having to do surgery) and despite the fact that it was a large soggy mass of straw and vegetation, it was not rotting or unpleasant at all when I removed it. I was incredibly surprised by that. You will know if things are turning bad because her breath will smell bad.
If you massage her, the scrambled egg may break down enough to pass through, but don't give her any more and concentrate on getting fluids going through her and plenty of massage. I had a broody bantam last year that was skin and bone under all those feathers and took nearly 2 weeks of daily massages and sloppy food before I got her going again, so a few days is not so bad as long as you get fluids into her. If her breath smells bad, acidified copper sulphate in the water should help... but not in a metal waterer.
