Hello and welcome to eHealth Forum!

A foul smelling and greenish or yellow discharge can be due to bacterial vaginosis. A fishy odor that is felt most after sex or masturbation or washing with soap goes in favor of bacterial vaginosis. Bacterial vaginosis is usually caused by Gardnerella vaginalis bacteria. It is not clear how the infection comes. It's not thought to be a STD. Treatment is usually by antibiotics.

Diagnosis is generally by a wet mount slide showing the presence of ‘clue cells’. Generally it is treated by metronidazole. After this course of metronidazole the smell usually goes away.

A greenish vaginal discharge can also be due to STD such as trichomoniasis. Again treatment is generally by metronidazole.

Please consult your doctor or gynecologist and get yourself examined as a confirmed diagnosis cannot be given on net. Hope this helps. Take care!