What’s going on with my armpit

Y’all I need help. I recently started using natural deodorant. At first I was using lemon to lightened my dark underarms and also neutralize any sweat. My underarms never felt so great and looked better. I noticed on them became very irritated and it hurt a lot. So I bought soma actual natural deodorant bc I thought the lemon was chemical burning it. My armpits were so irritated, they got even darker. After using Schmidt natural deodorants, now moth my armpits are very dark, and irritated. Please help!