It’s hard from this description to determine exactly what your problem is.
You’ve mentioned using saw dust. Don’t be misled that sawdust is some sort of cure for a poor fleshing job. You have to scrape the hide thoroughly in the first place.
Personally, I don’t use sawdust. I’ve tried it and it seems to make more mess than it cleans up. In the interest of starting a discussion here, I’m going to edit your topic title to see if we can get some input from other folks on using sawdust to clean up hides.
-- Hal