I smell something bad odor in my house and suspect I have mold. The problem is I don’t see anything. What can I do?

Check thoroughly...it might be building up mold at the ceiling.
Looks for water stains there.

Open all doors and windows when at home.

Avoid using ac even at night.

Place charcoals at various corners of house.

Check for dead lizards, cockroaches, rats under fridge, beds, sofas, washing machines etc.

Check for any water leaking or dampness on ceiling, wall or floor or window areas.

Waste water discharge area clean ?

Basin and kitchen sink trap cleaned ?

AC serviced ?