CS, I've had writhing dyskinesia (choreic movements) from day one with levadopa. What is more, I have diphasic chorea: I writhe when the l-dopa kicks in and I writhe when it wears off.
In between I have "peak-dose dyskinesia" which is a completely different set of ticks and involuntary movements. All of them become more virulent when I'm nervous or stressed out.

My neuro prescribed bromazepam (benzodiazepine), to take in an emergency, because he considers it less harmful than increasing my l-dopa dose. But as things are now, 13 years into PD, I would have to take it at least 3 times a day, and that I try to avoid.

Like you, I spend several hours a day writhing like an eel and it has become worse with Stalevo. Now it has become so unpredictable that I'm afraid to eat anything when I have to go somewhere. Needless to say that it makes my social life rather bland, I don't remember when I went out to dinner with friends.

Watch your diet, especially any stimulants (coffee, sugar, cool-aid, oreo cookies, etc) and the toxic "flavour enhancers" (MSG mostly) hidden in industrial packaged foods. One of the most distressing episodes I went through last summer was after having a cup of coffee and a tiny slice of berry pie at Ikea. That pie had more chemistry in it than berries. After 20 minutes I was in a fit of cramps and the wildest chorea I had ever experienced. We had to interrupt the shopping spree and my daughter drove me home in a state of despair, acting very much like that mentally retarded friend of yours you mention.

Since it all will get worse instead of better, I have decided to go ahead with DBS surgery, as I told you. Docs have confirmed that it will eliminate dysks, tremors and dystonia.