While a regular family doc or the free clinic in town might be able to at least diagnose this, you will wind up in either a neurologist office or, much better, an orthopedist's office. I think you have a damaged knee, and somewhere within all those joints is a few nerves all jammed up within those, and the signal is either on always and twitches, or off and you fall down. So, get a referral to or go to an orthopedist and let him get a scan, examine you, have you walk, etc., might have to wait a couple months to get in to seeone, and he will know exactly what to do for you.
In meantime, try cold for a while on that knee, and if it doesn't help, switch over to very warm on that knee, see if that at least helps. You can also buy at the pharmacy over the counter these sleeve-like stretchy things to put over an elbow or a knee. Try one of those on your knee and see if holding it together in a certain way helps or not. There is also tape you can buy, like boxer's tape, they also have it at the drugstore, and if you push around on your knee and can set off that throbbing nerve jerking around, then tape your knee to where it won't move and thus won't set off that wierd nerve. These are just remedial type things to do until you can see the ortho, because you DO need to see one, else you'll fall down the stairs or into a roadway.
Thanks ggreg! As of right now, 5:42 PM Monday, it is still twitching and getting violent also. I will talk to my mom about it (if it does not stop after I consume most foods that contain calcium and potassium.)