Breast skin problem or IBC?

I'm 31 years old and 21 weeks pregnant. 2 or 3 weeks ago I noticed some changes in the skin of my left breast. The skin in some areas was reddish and I noticed some stretch marks. Both breasts hurt, but they stopped after I changed the type of bra. I began to use cream to prevent stretch marks.  But now I can see clearly that on my left breast there is a round patch of thickened but soft skin of pinkish color right under my nipple. The nipple looks normal although the skin is a little bit dry. I got really scared when I checked the symptoms and it was a lot like IBC. Please can any one tell me if this is some kind of mastitis, problems from stetch marks, or common tissue changes during pregnancy. Or should I get really worried and go see a doctor?