Sore boobs sign of pregnancy?!

I have a sore BOOB(1) it's my right and it's in the centre and on the side.. I don't know if having one boob being sore is even a sign.. I'm on birth control and this month is my second month,I don't take the pill the same time every day and I occasionally miss it but I'll take it the next day.. 2 weeks ago me and my boyfriend of 3 years had sex 3 days in a row and he ejaculated in me and a few days later I've been cramping on and off.. I came down with the flu and was really sick for a few days also.. No one in my household was sick or even caught it even drinking after me,etc.