My cockatiel has one enlarged nostril. It's been increasingly getting bigger for about a month now. It doesn't seem to bother him at all though. No discharge, redness, coughing, irritation, or itchiness. It just doesn't look right and I don't want it to get any bigger (it's now twice the size of the other). He is six years old and mainly eats a seed diet. He's not fond of fruit at all, but likes greens. Any help as to what the culprit may be would be appreciated.
Thank you, Sarah.