What was the recipe, and what was the yeast. To ferment from 1.100 to 1.000 in a few days, I would say that you have a huge amount of simple sugars (honey, sugar, fruit juice, etc), and used a wine yeast, or other high gravity yeast.
Most ale yeasts will not ferment that low. That's 13% abv, most ale yeasts will give up before 12%, and even then you need to feed them the sugar in intervals to get there.
If it was brewed with malt extract, and you used a normal yeast, I would expect the final gravity for a 1.100 wort to get down somewhere in the region of 1.020-1.030 (70 to 80% apparent attenuation), giving 9.0%-10.5% abv.
Trub on the bottom doesn't mean a thing, it is just the solids settling out. A ring left by kraeusen around the top is a better indication of fermentation.