Large chicken pox infected or not?

its my 6th day of having chicken pox, most of them started to crust, but one, one of them on my forehead is really large (10 cent coin -size) and full of liquid, kind of grey-ish yellow-ish...and the pox is really bubbly. It hearts and itches, and tingles, more than all other pox, and my forehead swell a bit, not red, but just kind of swollen. I am not sure if i should worry about infection, or its just bec it is so large, its giving me more itch and pain and larger liquid bubble...