If your girlfriend has bacterial vaginosis or a yeast infrection it can get trapped under your foreskin. There, it can breed and spread, causing the foul odor. When you take a shower, you probably get rid of some of it (which decreases the smell) but it is still there. Switch to antibacterial soap (Like NuSkin or Dial) and see if that helps. If not, see a doctor.
I wouldn't be too worried. If you've already been to the doctor, and both you and your girlfriend have both checked out in good health, there isn't really too much to be concerned about.
CurleyGirl7 has some good advice, if your girlfriend does have a yeast infection or vaginosis, that could very well be causing the smell.
Don't doubt your girlfriend like someone suggested, if this is really concerning you, I doubt your girlfriend would lie about being healthy or not. After all if it was serious, it could be dangerous to her too.
This site complies with the HONcode standard for trustworthy health information.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.