What Does The Knot On The Hip Indicate?

i was told that a knot on my hip may be the result of scar tissue forming from an injection site by my dr. She said to watch it and if its appearance changes to let her know. It swelled and became red like infected. I went to her and she thinks it a boil. I put antibiotic cream on it and started on antibiotics. Now it opened and it drained. After it drained, now there is a lot of white firm tissue sticking out, not like puss but it looks like cotton wadding that has been in there for a long time. Is that possible ? something left over from a surgery trying to expel itself?