Black Skin on Toe

Hello, I'm 19 years old and male. Recently I went to see my podiatrist for an ingrown toenail and also asked him about a corn that was developing on my toe. He said that it was the result of the adjacent toe rubbing against it and gave me a pad to wear between them. I tried the pad for a little while but it didn't help, so I eventually bought some corn removing band aids at a drug store. I used the band aids for a few weeks; they significantly reduced the size of the corn but failed to remove it completely. Another week or two went by and I noticed at some point the corn skin was feeling dead/scabby and I was basically able to just peel it off. There really wasn't any drainage, not blood maybe a LITTLE puss. Anyway, I've now noticed that the skin where the corn was is completely black. I would really appreciate it if someone could tell me what this might be as I cannot see a doctor for about 2 weeks. I can answer any other questions if needed. Thanks in advance.