Whom does he look for?

Whom he is looked after for?

Who is looked after for him?

Who is looked for by him?

Whom he looked after by?

All of the above

We change WHOM into who. Don't forget keeping the ? at the end.

Formula:
Who + helping verb + Subject + V3 + Other objects + ?(question mark).

Active: Whom does he look for?

Passive: Who is looked for by him?