I found a lump last year and had a referral to breast clinic. I had an examination, mammogram, ultrasound and biopsy. I worried myself sick waiting for the follow up appointment with results, thanks to Dr Google. 
It turned out to be a cyst that had become infected, that's why I was experiencing pain and redness.

Take it as a good sign that your GP did not make an immediate referral. Continue with the antibiotics and if these further symptoms are really worrying for you then call your GP back and ask for some advice.

Most importantly try not to worry too much unless a professional gives you a reason too. When I got my biopsy results I felt so relieved but also like an idiot for immediately jumping to the worst case scenario in my head.

I hope all goes well x