Lump in right breast nearest to arm pit

I've recently found a lump which is located in my right breast nearest to my arm pit, I found this out and my heart suddenly sunk. I went to the doctors straight away to make an appointment and all I got told was it is swelling off where my bra has been too tight and has been rubbing against my breast. 1 week and a day after going to the doctors it is still the same and is very easy to move around, sometimes hurts also. If someone could help me with this it would be great as I don't know what to do.