yeah, thats a glitch that i guess they couldn't fix, so you'll have to load an old save
forget it,haha
i completed everything other than that
umm if you go to the alchemy shop in the market district, you can go down stairs and steal some, and during the dark brother hood quest line when you become a listener when you save the night mother *you have to be in the tomb, if you've done it you cant do it* and there are 1 or 2 peices of blood grass next to her corpse
but check in alchemy shops
i already did that brotherhood quest, but listen the lady in the arcane university sells bloodgrass, but the lady who makes the cure doesn't give me the option of giving it to her.