I used to have that bad odor quite often, it smelled a little like cat spray. I was having problems with chemical sensitities and that meant to me that my liver wasn't working well enough to remove pollutants from the body. I read in my biochemistry book that our bodies have another way of removing pollutants. In the blood the toxins are linked up to some sulfur containing amino acids and then excreted by our apocrine (sweat) glands. Sulfur compounds are very smelly, they make our feces smell bad and the bad smelling compound in cat spray is very similar to what is excreted in our sweat. Eating foods with lots of sulfur such as garlic will make a person with a toxic build-up sweat out more of these bad smelling molecules.
In my case the bad smell usually came after I ate a prepared food probably because they had small amounts of toxins from disinfectants or other things used in preparing the food. This rarely happened when I prepared all my own food. You might want to ask your doctor how to be detoxified or check around online for ways of improving the health of your liver.
Hope this helps.
This might be due to hormonal changes. I'd see my gyno.