Last Night While Sitting Outside I Felt Almost Like A

Last night while sitting outside i felt almost like a cramp developing in the ball of my right foot...it almost had a burning sensation....a huge lump appeared just below the toe next to big toe...skin turned white and it felt like a golf ball under my skin....i couldn't flex my foot or walk on it because lump was so big ....i put my foot in cool water and the lump did go down a bit after an hour or so ...today its still there but smaller and no problems walking or flexing my foot.....i do not see any entry site where i may have been biten and it felt like something from inside from under my skin not on the surface....very strange ...what could it possibly be?