Learn English – Difference between had been and went to

She had been treated with these medicine in 2004 - (correct) It's in past participle tense. It means in the past the action occurred over a specified amount of time.

She had being treated with these medicine in 2004 - (Incorrect) We say "She is/was being treated...."

And as for your last two examples they are also incorrect. You need to omit "as"

She said she had earlier been treated by the Guptas, in May 2003 (correct)

The news left me stunned.

The drink left me feeling queasy.

The boiler explosion left the building in ruins.

The boiler explosion left the building looking as though it had been hit by an earthquake.

to leave [something/someone] {complement} can be understood to mean "to put [something/someone] into the state expressed by {complement}.

States are expressed by adjectives, prepositional phrases, and non-finite forms of verbs used adjectivally as object complements (phrases introduced by the present participle, or the past participle as adjective).

To express a resultant state, we cannot use a finite (tensed) verb like looked:

It left the embassy looked... ^{ungrammatical}

and the past participle of look, looked, does not express a resultant state and thus cannot be used as an adjectival object complement. If we look at something, it does not become looked (but looked at). Look is unlike see in that regard. When we see something, it does become seen.

In the explosion example, look means "to seem, to appear". The past participle of that verb does not express a resultant state either.

P.S. To hone this a bit, it not just a resulant state but a state that is the direct result of subject's action. The verb whose past participle form is used as the object complement must express an action that the subject does. For that reason, we cannot say:

The storm left many trees fallen. ^{ungrammatical}