Pregnancy can cause the breast to become tender and itch. So, take a pregnancy test and see if you have missed your periods. However the itch could be due to dermatitis, Paget’s disease of the breast, or eczema. We have a similar discussion on MedHelp which you can read: http://www.medhelp.org/forums/BreastCancer/messages/3934.html
Fibroadenosis of breast should also be looked into. Cancer of the breast or duct too is a possibility. Certain breast rashes are specific to breast like inflammatory breast cancer, Paget’s disease of the breast, mammary duct ectasia, and mastitis. Since you have a strong family history and you went to the doctor before the rash started, then you must get it checked once.
Other causes of rash on the breast can be psoriasis, atopic dermatitis, seborrhagic dermatitis, fungal infection, dryness, and eczema. All these can cause rash elsewhere in the body too. Please discuss this with your doctor. It is difficult to comment further without examining the rash.
Please consult your PCP for primary examination followed by proper referral. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.