What Causes Purple Growth In The Nostrils?

My son is 2 1/2 years old. He has a large purple growth in the back of his right nostril and his left nostril is completely closed with the same purple growth. He has no coughing, sneezing, headaches, runny nose, congestion or any other symptom that would point towards a cold/flu. He has had this for 2 weeks now and just recently starting saying that his nose hurts when I touch it. I've heard of nasal polyps before but I haven't read anything about a 2 1/2 year old having them. When he was a new born and all the way up until he was around 6 months old he used to get nose bleeds but then they stopped. He has an appointment tomorrow with his doctor, what should I expect? Should I be worried?