what is this under my armpit

Zinky • Pale ghostie...Just a Supernatural fan, on Team Dean, in a relationship, makeup and Music. 🎶👻🤘🏻💅🏻💄👑
I noticed it a few weeks ago. It itches badly occasionally. I'm scared to shave or even
Put deodorant on. A co
Worker says it's a yeast infection? Any suggestions to help until I can get
To the doctors next week? 
Update it's starting to show up on my other armpit now, it's tiny compared to the other one but it's the same. Itchy, burns and raised.