What can I do to get my washer to stop smelling like something rotten?

I would say about two weeks ago I washed clothes and left for work, my husband had forgotten to put them in the dryer. That night when I came home from work he lied and said he dried and put them away. I didn't think to look in the washer till a couple days later when I was searching and searching for this rotting smell in my house. I found out it was indeed my washer with two day old washed clothes. I rewashed them right away, my clothes didn't smell after I washed them and dried them but my washer still has that rotten smell. If anyone has any ideas to getting rid of the smell please let me know, before I have a repair-man come out and take a look at it. Keep in mind my house smells like mildew very bad. I'll take all the help I can get.