If you would consider the odor a metallic, unpleasant smell then perhaps this is due to an overgrowth of normal bacteria in the vagina called (bacterial vaginosis--BV). This occurs commonly in women and is treated with antibiotics prescribed by your doctor. Until you can see your doctor, you can use an over the counter product called RepHresh to restore your vaginal pH and treat the odor. Another possibility is a sexually transmitted infection. If you have not been tested since you've been with your current partner, you may certainly request testing to be sure. You can find more information about RepHresh at the website below. I hope this helps. Feel free to ask additional questions, if necessary. Best wishes.
Then you smell this because your discharge has an odor in general. This does not help identify the actual cause. Your doctor will need to use a q-tip to take a sample of your discharge and review it under the microscope to determine which of the above is causing the odor.