So frustrated, why does my dog always stink?

I can't snuggle her because she consistently smells bad (like stale tortilla chips). I give her a bath once every 1-2 weeks. She does not have an infection, with her thin coat and my eagle eye, I have not seen anything, nor has she displayed unhealthy behavior. She is a miniature schnauzer and is 3y/o. She does have bad B.O. after running in the field with hubby, but even after the B.O. fades (well into the next day) she still smells bad. I've even washed her bed, and still stinky! Please help :(