You could have a protazoa, a bacterial infection or a yeast infection. The only way to know is to get it cultured. Go to Planned Parenthood or another clinic if you have limited funds or are embarassed.
Most of the pungent oders are easily cured if you both take medication at the same time. Sometimes it is an inserted med for the ladies and a creme for the gents. Sometimes it is a pill.
Ignoring it may cause other problem, so do it together and make it something you can laugh together about after it is over.