Hi. I'm not sure where to start.

im 29, never had any breast problems. 

approx 2 year ago I noticed my left nipple kept going inverted which it never used to do. I thought nothing of it. My breast then started looking bruised in one area, always the same area, bruised and kinda like thread veins. I also ignored it. I'm stupid I know. Then, lately, the underside of the breast and sometimes my nipple loses all sensation?!

Anyway. A couple week ago I noticed a small lump and thought right okay... I should see a doc. A doctor said it was possibly an infection in the tissue. Gave me antibiotics and sent me on my way. I felt more relieved.

My boob started going bruised looking again and the lump felt a little tender. I went back and the second doc said he's referred me to breast clinic urgently. I was given an appointment two days later. It's on Tuesday. 
what will they do at this appointment?! Could someone please talk me through it? I am riddled with anxiety over this. 
thank you & sending love, strength and hope to everyone