Yellow oozing after otoplasty may be an infection till proven otherwise.
Based on your history, you could have another extruding suture with possible infection. Ear cartilage infections may benefit from antibiotic therapy, so you should let your surgeon know what's happening as soon as possible.
I wish you well.
Possible infected suture
Keep the area clean with soap and water. It sounds like you may have an infected suture. See your Plastic Surgeon as soon as possible.
Infected suture knot after an otoplasty
Wash the area with soap and water until you can get in to see your plastic surgeon. Most likely this is a suture knot infection and the suture will need to be removed.