4 months later, superficial fistula not healed and has growth

I know the obvious answer is to return to the doctor and I probably will but I was wondering if anyone else had this problem.

In late September I had surgery to repair a superficial fistula. It is still not fully healed and I have noticed a strange growth. For a while I would look and I'd find a pink line off the side of my wound and I thought I had somehow been tearing the side because of how I sit or something.

The line would go away and reappear. But today I discovered that line was mobile. It is a very long, thin strip of..something. Like an extremely long skin tag. There's a weird lip of sorts on my wound where it's harder to see and it seems like it's coming from in that area.

What is this thing?