What the Hell is on My Foot!?

Earlier today, upon returning from a walk to the Ferry Building (2.5 miles round trip), I noticed a strange bump on the top of my right foot.  The bump is pretty hard, about the size of a marble, and doesn't hurt at all.  Weird right!? I of course went on a Googling expedition to find out what the hell it is.  After some searches, I found out that it is likely a ganglion cyst that developed from injuring my foot while walking 12-14 miles in a couple of days last week while in Washington, DC.  Either that or it happened when I twisted my foot walking to work the other day after my return from DC.  Either way this thing on my foot looks really weird, I certainly hope it goes away on its own soon.