What Causes Foul Smell In Nose While Using Meth?

Yes I'm just trying to figure out the answer to something . Every time I use meth I tend to smell this strong fart like smelling odor. And I can't tell if it's my breath, vaginal area, or if it's all in my head. I constantly smell it and it's so strong but when I ask friends or family if they smell it they have replied no but I'm not sure if they are being truthful or just trying to make me feel better