Really itchy armpit? Please help!

I’ve noticed that underneath my armpit is extremely itchy and there is what looks like a scratch / cut, but I know for certain I haven’t cut or scratched beneath my armpit! What could this be? It itches on and off, and when I start itching it, I don’t want to stop.

I have not changed deodorant or body wash so I know it’s not that.

Please excuse the hair stubble, lol!

I did the worst thing possible and googled it and it popped up that an itchy armpit could be linked to lymphoma cancer, and now I’m terrified! I’m only 17!

Please help!