Getting rid of smell under armpits

Hi There,   A while ago I started noticing a smell under my righ armpit, it kind of appeared suddenly but I cannot think of a certain cause for it. I read on a newspaper website that you yourself did have an issue with smelly armpits and you kind of made it go away by wearing an old t shirt all the time (https://www.volkskrant.nl/wetenschap/nooit-meer-stinkoksels~be128982/).  Do you think such an approach is useful for someone to try? Or do you have other ideas to get rid of this problem?