My breast has been itching on and off for the last few weeks. Three days ago I noticed a sore under my left breast. Should I be worried? I also have similar sores inside my mouth that I noticed around the same time. Could these be linked? My left breast aches.. and hurts when I wear my bra. Today I'm home sick with a very nauses stomach. I'm scared that all this could be linked. My aunt passed away from cancer 2 years ago... When she had breast cancer I remember her telling me that sores would appear on her breasts too.