I have this foul smell from my vagina after having sex. is this from the semen and how can i help rid of the smell?

Bacterial vaginosis: If it is a fishy odor, it would point towards the presence of gardnerella vaginalis bacteria. Your partner could harbor the bacteria in his prostate gland. Males typically don't get tested for BV. In some states of the US, partner treatment is legal. If you see your gynecologist and a diagnosis of BV is established, your doctor may be willing to treat your partner as well.

Not normal: I would advise you to see your gynecologist soon for evaluation because the symptom that you are having is not normal. It may not be caused by the semen.

Need Evaluation: Vaginal discharge, and irritation following recent unprotected sexual intercourse may be indicative of sexually-transmitted disease. Consult your physician as soon as possible, to prevent further complication.

Try condom: to see if the smell is from semen, try sex with a condom. If you still smell it then it is from the vagina itself