Record the pattern
Note which room smells, whether the odor changes after rain or appliance use, and whether a leak occurred previously. These observations can help a professional decide where to investigate; they do not prove a particular mold species or health effect.
Distinguish investigation from cleanup
If you do not know the source, ask about an inspection or moisture assessment first. A remediation service addresses an identified problem; testing-only enquiries may need a different provider. Clearly describing your needs can prevent the wrong appointment.
Do not open a wall just to look
EPA notes that investigating hidden mold can be difficult and that disturbing affected material can spread spores. Seek experienced help when hidden growth is suspected rather than dismantling finishes to confirm it yourself.
What to say when calling
Describe the odor, room, previous leaks, visible stains and whether the smell persists. Ask what the assessment includes and whether independent testing is necessary for your particular situation.