D.N.
Add about a cup of white vinegar. I started using vinegar in the wash when my daughters forgot to take the towels out of the washer and they sat overnight since I put them in at night and then all day. Horrible. I did try washing again but still had that smell. Now, I add vinegar all the time and even when they just sit in the closet, they do not get that stale smell. And I have noticed they feel better as well. No need to dry the clothes first.