Musty rainy-season room with black spots on the Unawatuna wall — sleep one night or demand a move?

Damp smell after heavy rain is common on the south coast; visible black spots and a cough are a fair reason to ask for another room the same day — not to wait for a dehumidifier promise. Be polite and specific: show the wall, mention breathing, ask for a drier room or early checkout without drama. Good hosts move you if they can; if every room is the same, consider changing guesthouses rather than toughing out three nights. I am not a doctor — if anyone feels wheezy, prioritize health over the booking rate. Photograph the spots for the platform chat if you need a partial refund discussion later.