Posting here for a wider variety of answers.
I have always been worried about smelling and thus, very careful about my personal hygiene. I've never ever smelt before. Lately, my armpits have started smelling of onion!

I shower twice a day, wear cotton clothes, change clothes regularly, wear Mitchum antiperspirant deodorant, don't get particularly sweaty. I come out of the shower, smelling fine and then 15 mins later, my 'pits smell!
I've recently been very unwell and lost lots of weight, not sure if my ill health has any connection with the new smell.
It's making me feel really fucking miserable and paranoid, even though apparently no one can smell me even if they get up close to my armpit.