You need to get a culture sensitivity of the vaginal discharge done to rule out any vaginal infection as mostly it is the cause of smelly discharge. It can be due to vaginal yeast infection or bacterial vaginosis as well.
For candidiasis or yeast infection, Take some precautionary measures like avoid wearing tight fitting clothing like jeans and pantyhose and underwear made from synthetic fibresRemove wet or damp bathing suits immediately after swimming,avoid douching, perfumed soaps, bubble baths and toiletries,change underwear daily,wash underwear in hot water (to destroy fungi) and double rinse (to remove any irritating detergent) and take adequate nutrition and sleep.Also use some antifungal pessaries like clotrimazole (Femizole-7), miconazole (Monistat-Derm, Monistat Vaginal) or nystatin which are available over the counter.If still the symptoms persist then oral antifungals may be needed.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I know it’s 4 years late but is it possible you left a tampon in and forgot about it?
That would explain the symptoms and smell you describe.