Skyrim: Help with purity quest

[Kr/\zy]

Hi all, i have a really annoying issue that bothers me: i can't get to start the purity quest (Companions). Things i already tried out:

- Setstage cr13 10, 20, 100. No effect;
- Done a lot of radiant quests for both brothers;
- Brought Vilkas to Ysgramor's tomb, without effect.

I've done all of this stuff with 3 Glenmoril witches's heads in my invenctory.
In the last mission, after i cured Kodlak, i've cured myself too but then reaquired the beast blood again (Aela) to finish the Totems of Hircine and Purity quests. I've found the 3 totems, but Vilkas nor Farkas won't give me their purity quests dialogue, even after a lot of radiant quests i have done for them. I am a kind of a completionist so please help.

PS I've already been into other forums and wikis, without success.

[FFL2and3rocks]

Each game on Steam has its own forum, try there.