Sounds like most fermentations to me. When the krausen falls, I always get gunk floating on the surface for a good week afterwards. It falls back in and the solids eventually settle out in the yeast cake.
Dunno about the astringency, but fermenting beer can have all kinds of odd smells and tastes as it's going. If it's not jumping out and smacking you in the face, odds are it's fine.
"Science + beer = good!"