Leakage from incision

Hi ladies, I am just looking for some advice.  I had a lump and lymph node removed last week.  The incision under my arm started leaking quiet a bit today (yellow in colour but no strong odour).  I went to the clinic and the doctor drained 15ml from the incision and said it was only beginning to become infected.  He perscribed me antibiotics.

 

I am just wondering if it is normal that it is still leaking and should I be worried.  I was in too much of a fluster to ask the doctor the 'what if questions'.  Has anyone else had this experience?