How do I tell my girlfriend she smells bad

So this is my (20F) first girlfriend (19F). We had sex last week for the first time and she only focused on me. This week I wanted to please her too. She expressed nerves about not tasting good and smelling bad. She told me she knows her ph is off. I went down on her and the smell was like pure BO. The taste was fine but the smell was so bad. I really wanna go down on her but I couldn't handle the smell. I felt so bad. How can I help her and tell her?? I really want us to have good sex and I really wanna please her. Please me help me. I don't want this to ruin our relationship.

Edit: omg I'm a lesbian please stop giving me advice like I'm a straight man 😭