You have to check this out with your doctor, as he/she will be much more knowledgable than any of us and he/she will know if there is anything to worry about, and further testing indicated.
Many strange things happen when you are pregnant; it could even be a milk duct filling up.
As a rule, caner in the breast is not painful.
Yet, you have all my sympathy about being nervous, as I think we would all be, especially while pregnant.
All the best, KATRIN
Have your OB/GYN check it out tomorrow. Don't be afraid, take control and have it checked out. I was just diagnosed with breast cancer and am dealing with that. I know the fear you're talking about, but for your baby's health and you own, check it out tomorrow!