Why do I smell down there?

I been noticing I have a foul smell that I could smell when I’m just sitting there. Kinda embarrassing because I don’t know why I smell. I have a boyfriend and he’s the only one I have had intercourse with. My discharge is off white yellow and today I smelled like it I was on my period but I don’t start till another 5 days but then i also smelled like a mayonnaise smell. I usually will smell sorta musty but after it’s been a long day of work. Could it be I’m wearing to tight of clothes or could I have something. I don’t want to go to the doctors either I hope it could be something I could fix on my own but I’m not sure what to do. Why do I smell?