Vagina smells like onions??

When i sweat down there it smells like onions and it’s really strong. I have no idea why, and this has never happened before. I’ve been buying underwear with thinner material lately, so maybe that’s the reason idk. But i also started birth control a few months ago. I’m not sure what the reason is but i don’t eat onions so that’s not it. Even the deodorant isn’t helping. Any suggestions?