I'm still confused about which part of the past few episodes have been real and which have been hallucinations! Can someone please explain to me?

We know for sure that everything (involving House and/or Cuddy) that happened after Cuddy sinabi "Screw you" in Under My Skin was a delusion. As far as Both Sides Now, the lipstick was actually a pill bottle. Everything else is up for debate.

It's best to make up your own mind on that. Just watch any episode you're not sure of again on a site like this one; link

i agree with mrshouse; everything was a hallucination after cuddy sinabi 'screw you.' thats why, in the end of both sides now, all the scenes with house and cuddy were split with scenes of house going through them alone, to ipakita his hallucinations (being with cuddy, detoxing) versus the reality (being alone, taking pills).

After the point in "Under My Skin" where Cuddy says 'Screw you', and he tells her he needs her and everything, it was a hallucination. In reality, she walked out. This is why we see the split on his recollection of the supposed 'huddy' sex that night. The half with the sex, wasn't real. The half where it is just him, alone, and still popping pills, is what really happened. Throughout the episode you come to learn that the left side of your brain makes up who you are; your story. That is why Amber says "So this is the story you made up about yourself, it's a nice one..." and then you see Kutner say "Too bad it isn't true" (sorry if thats not exact, but you know what I'm talking about) the lipstick tube wasn't real, because Cuddy never spent the night at House's, as we were tricked into thinking. All it was was the vicodin, the pill bottle, that everytime we saw him holding the lipstick/playing with it, he was really holding the vicodin bottle.

At the end of this episode, we see that House has become truly delusional; it's not just about hallucinations anymore. This is why he has to go to the psychiatric hospital. Hope this cleared things up a bit :)