Hi! 2 Weeks Ago Me And My Bf Where Having

Hi! 2 weeks ago me and my bf where having intercourse and he started sucking on my left breast and it was not painful or hurt at all! But the next day my nipple and breast was very tender and sore! And now I feel a hard lump near my nipple and it doesn't move when I touch it and is very painful and swollen! I saw my doctor and he has me set up for a ultrasound on my left breast and I feel so embarrassed I'm not sure if this is from intercourse or if this is something more serious!