### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
Hi. I have a 15 month old child and when I was breastfeeding I developed what I assumed was a blood blister on my nipple. It is a little black mark which appeared from no-where. After 6 months of it being there I saw the doctor who referred me to a dermatologist. She had a look and said it is not a blood blister, but would like to get a second opinion, so I am currently (5 weeks later) waiting for another appointment with a different dermatologist. The dermatologist mentioned skin cancer, and breast surgery, but I think it was more a case of letting me know the worst so I would be prepared just incase. However, I also have 2 lumps in my armpit which I didnt even think to mention about. One which has been there about 8 months, and the other which has developed recently. Theyre not painful and theyre not huge, but theyre definately there. I have just in the past week stopped breastfeeding and so I am assuming the pain in my breast with the mark is down to a blocked duct or mastitis which will clear soon enough.

### output:

Welcome to Chat Doctor .1. You are right with your possible causes after the breastfeeding like ductal blockage and dilatation and inflammatory changes.2. The changes in the breast you are experiencing with a blister and lymph nodal enlargement is giving a suspicion of any breast lesion.3. In this case an ultrasound breast will be ideal - it will help in detecting the nature of the lump its source and where all extending.4. After that if required an FNAC - fine needle aspiration cytology would help to know the nature of cells.5. So get a scan done, as its more informative. Good luck with your appointment. Hope it helps you. Wish you a good health. Anything to ask ? Do not hesitate. Thank you.