Sudden intense BO and only on my left armpit

(English is my second language im sorry for the errors in grammar and spelling)
Ive been struggling with BO since i was 9, im 17 now(F) and I still have it. For the past few months, i was able to manage it with just deodorant and proper hygiene. But there will still be times where i would stink horribly if i skip a day to shower or if dont put deodorant.
Last tuesday i got home from school and i immediately swipe off the  sweat on my pits and i was surprised  when I notice a smell, normally I dont smell anything after a day at school. The odor is different from the normal BO i get when i sweat a lot, usually it smells like onion but this new one smells tangy and sour. Another thing is that it only smell on my left armpit and not on the right (im right handed). I didnt overthink it because i thought i could solve it with betadine skin cleanser or just by showering with antibacterial soap. But it shookt me when just after a second i got out of the shower the smell came back. I skipped school for 4 days now and the odor is still here, i tried everything but it seems like it cant be controlled. I feel hopeless and depressed, i dont know what to do anymore, my BO has never gotten this awful.