I just got the same syptoms myself...very strange especially since I have very numb nipples normally-not at all senstitive. I didn't wear a nightshirt to bed the other day and woke with this condition. Sheets were clean and had just been washed a few days before...although my cat sleeps with me...maybe I'm allergic to her? I thought it could either my hormones changing...breast cancer (I'm a bit of a hypocondriac), or allergy to my cat.
I do get the same symptom every month before my period. Very itchy nipples. Have you seen a doctor yourself to find out the root cause? What birth control are you if any? It's happend to me since I started on the Mirena.
I sometimes get itchy nipples around the time of my period. I just put eucerin on them or a really thick mousterizer and it goes away. I would try this and if that doesn't help I would prob see dr.