Marble size knot in hip joint

I have been having problems with my left hip for about 8 weeks now and today I found a marble sized knot in my  left hip joint, which is painful, what would cause something like this? Also, the other morning when I woke up, I could barely put any weight on my right hip, which later for several days; what would cause pain like that, all of a sudden?

[Froggier65]

I should also mention that I fell (slid) down a flight of stairs a couple years ago and never went to the doctor to be checked; could I have had a hairline fracture that turned into a break after so long?