This is Dr. David
you can get mastitis if bacteria get into the breast through the blood system or nipple.
chance of breast cancer would be small at your age but not zero.
it is unfortunate that you did not let your doctor examine you.
you are doing yourself a dis-service by not not allowing your doctor to examine your breast and skin there
I can't examine you either.
ducts in the breast sometimes can get blocked.
warm compresses can help open up ducts in the breast.