It sounds like you have been experiencing malodorous vaginal discharge from years and I recommend that you speak with an OBGYN. From your description, it is possible that you are experiencing a condition called bacterial vaginosis which is an overgrowth of bacteria in the vagina. It can cause white to clear discharge that can smell fishy at times. It doesn't cause much pain or discomfort but it can cause some itching. Bacterial vaginosis is not known to be transmitted sexually. It is most likely caused by an imbalance of "good" and "bad" bacteria in the vagina. All women have lactobacillus, which is a type of bacteria, in the vagina. They help create an acidic environment in the vagina that kills off other organisms; thus, the vagina is known to be a self cleaning system that does not need "extra" cleaning. If you do clean it with harsh soaps or other cleaning reagents, it can kill the beneficial lactobacillus. The vagina will no longer have the acidic environment that protects it from other organisms. This often leads to overgrowth of other bacteria or yeasts that can cause problems. You should may an appointment with an OBGYN doctor
to have it examined to ensure there are no concerning medical conditions that is contributing to your condition.