if the room is damp and mildewy, the clothes will smell that way. to combat mildew,wash down the walls and floor, wherever you can reach with a bleach solution, about 1/4 c. to 1 gallon water. i use more bleach, but you decide. the bleach kills all mold and mildew. if you have windows, open them.
don't leave wet clothes in the washer. dry them right off. as the others have said, vinegar or borax will help. if the room gets chilly try to heat it up a little, it will help the room to dry.
did you sniff inside the washer and dryer? i don't think the small is coming from there. do you hang wet clothes in there to dry? that causes mildew, too. imo
edit: leave little boxes of cornstarch around to absorb the odors, change them regularly.