So I'm in the midst of my second playthrough of New Vegas, and one of my goals this time around is to complete all of the companion sidequests. So far I've done all of them, except Lily's - I just can't make progress for some reason.

I've had her as a companion for a while, exhausted all normal dialogue options, and even got through her first psychotic break, but for the life of me I just cannot figure out how to get to the point where you tell her how much medicine to take. It's especially frustrating since I do recall having that dialogue with her in my first playthrough - and I wasn't even specifically trying to get it back then.

So, what am I missing here? Do I need to take her someplace special or talk to some specific person before it happens? Or try to get her to have another psychotic break? Or is it on some kind of timer like the ED-E messages?

I know, this problem is only a minor one in the scheme of things, but it is really starting to annoy me so any help would be appreciated.