What Causes Breast Surgery Site Discomfort With Discoloration?

I had breast surgery a month ago where I had a non-cancerous lump removed. At the site of the lump, I had problems with the area not draining. The doctor manually removed the fluid. The fluid was tested and no infection was found. My last visit to the doctor 2 weeks ago was much better. Now I am starting to feel some discomfort in that same area and the area where the lump was removed still is purpleish/red. What could be the cause? Should I have this re-examined?