I had the same this week I’m 5 weeks post op, but mine was more a white blister on my left nipple incision which burst wen I touched it – slight green stuff and blood came out, sorry to be disgusting! It was just a stitch dissolving and tests showed no infection, same thing happened again last night on my right nipple incision! So 3 visits to the nurse in one week and back again tomorrow! Those car park machines love me this week! Hopefully it will be nothing for you to worry about, have u called the nurse?
X