Underarm brightening

Okay, this is embarrassing. Which is why I would prefer not to show pictures at the risk of my identity being like, discovered on here. I am white with very pale skin, but I’ve noticed recently that my underarms are literally, like… yellow. I use Secret’s stress response deodorant. I think I have sensitive skin because I had tried another deodorant at one point and it made me itchy. I’m open to trying another one potentially if it doesn’t irritate my skin, but I don’t know if deodorant is the culprit here.
One night when we had all gone out, my friend’s boyfriend was laughing hysterically at a picture where it was visible because in the picture, a friend and I were flexing our biceps. Granted the boyfriend was fairly drunk, but I was really not happy about that at all.
Since then I’m kind of looking for a solution. I don’t know if it’s exfoliator or what. A few years ago, when I was in high school, I had tried baking soda with hydrogen peroxide. But something tells me that’s not advisable. So, yeah.. if anyone has ideas, throw them at me. Thanks.