PCOS and Prom... Help?


So... I have an issue.

I'm 17 and have PCOS. Prom has snuck up on me so fast it's kind of ridiculous, and I'm super worried about my dark underarms. I'm wearing a dress with spaghetti straps and I really don't want to wear a cardigan with my dress because I feel like it would be too hot once I started dancing with all the people around.

Prom is Saturday and I'm not sure if I can find a way to get rid of the dark skin under my arms. They're kind of embarrassing and I'm afraid of my classmates seeing them. Does anyone know what I can do with such short notice? I would appreciate any suggestions. Thanks!