Pink Crystal is Pinkie that is in Lostham. If you touch him, he will Heal your HP and MP.
About the crystal to find in the door. First you need to enter in Edna's Room, to enter you must hit the pillars in the left of the entrance of her place. There are three pillars.
But first, you must wash the scroll you got in the water of the pharaoh dream
In the Book
: "Did you put your name into the Goblet of Fire, Harry?"
he asked calmly.In the Movie