changes in my cycle?

So my period has always seemed normal, it's comes on time, normal(for me) bleeding, but a few months ago I got this itch two days before my period and it  lasted until my period ended. I used to have a six-seven day long bleeding period but in the last few months it's gone down to three-four days. At the start of my next period the itch will come back, but the blood will be darker, this has been going on for three or four months, my last period started yesterday and the first blood was nearly black.... and the itch came with a vengeance two days ago. I'm making an appointment with my obgyn, any advise or ideas as to what's wrong?