I don't remember the name of the story or what site I read it on. However I remember the following points.
Harry has some sort of creature inheritance (snake-based)
his skin is peeling off and he hides it with gloves
I believe it takes place in 5th year as Umbridge is in it
Harry runs away when Umbridge tries to remove the gloves and glamours
Harry hides behind a armor or in an alcove
a small carving of a snake on the wall talks to him
he goes into the chamber
he finds Salazar's body in a coffin/sarcophagus
Salazar's name is carved in to a door by Godric after Godric kills him
It has been a long time so I may be misremembering.