When does the next phase of your turn begin?

[FossilMan]

I am not quite a new Munchkin player but I thought this question would go nicely in this forum.

We were playing a game of Apocalypse the other night and the person to my right asked if she could use the Scientist power to trade in a door for the treasure. I thought that the answer should be no because she had already looted the room and was already in the next phase of her turn. The power says that before the charity phase of your turn. Another player argued that she could still be in the loot the room phase.

The question:
When does the next phase of your turn begin? Is it after you draw the loot the room card? Additionally, does your turn end and the next begin immediately after charity is over?

To me the rules cover this quite clearly and don't say anything about a "buffer" time to read cards and therefore would move directly to the next phase after the action is completed but if the other player thought that it could then I could be wrong. Thank you guys!