Does anyone know what this is?

Kelly • I Stan BTS❤️❤️

Hey 👋

I’m 13 turning 14 in May and I was just wondering if anyone can help me

So I’m on my period right now and the last time I had it, Small dots came up on my chest, just under my neck...And the back of my neck is itchy almost all the time, when my period ends it stops and the little bumps go away, maybe it’s just a coincidence, I don’t know. Does anyone know what this could be?

Thanks