I don't know when your last test was at your GYN, but a foul smelling discharge is usually associated with something like Bacterial Vaginosis or Trichomoniasis. Both Bacterial Vaginosis and Trichomoniasis requires antibiotics such as Flagyl to clear up completely. Once you start a treatment with antibiotics, you cannot have any type of sexual contact or you will end up spreading it back and forth from your partner back to you. Sometimes, males do not always have symptoms as females do and may have no symptoms at all, so the spreading can take place without you even knowing it.
Also, douching is not a good idea at all. This can disrupt the normal flora of the vaginal canal and cause the Bacterial Vaginosis. Both can/will cause a foul discharge and painful intercourse.
You mentioned Pelvic Inflammatory Disease....this too, can cause symptoms similar to what you have described but left untreated can cause infertility and other problems. Again.....cured with antibiotics. Over the counter treatments simply do not work. You have noticed this by now.
I think it is prudent that you go ahead and get re-swabbed for infection and start an antibiotic and bare in mind that BV is sometimes hard to treat and may take 2 rounds of antibiotics for it to completely go away.
Hope this helps!
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