Knot on foot

I’ve got a knot on the top of my right foot, toward the inside, it’s about the size of a Nickel, it’s hard (like a bone).
I’ve got no pain, there is no bruising, no redness or anything and it showed up in less than 12 hours.
I’ve not been able to find anything about this, I”m confused!!!
I’ve not been to the doc.