Twitching for almost 2 years now...
This forum is for questions and support regarding neurology issues such as:
Alzheimer's Disease,
ALS,
Autism, Brain Cancer,
Cerebral Palsy, Chronic Pain,
Epilepsy,
Fibromyalgia, Headaches, MS, Neuralgia, Neuropathy, Parkinson's Disease, RSD, Sleep Disorders,
Stroke, Traumatic Brain Injury

Has the twitching gotten increasingly worse over the last two years or has it basically stayed the same? Above the knee sounds like the large muscle (the quadracep) that's twitching and locking. The back above the knee would probably be you Hamstring. When those lock up that must be painful.
Do you have twitching anywhere else on your body, like your face, hand tremors, feet, any myclonic jerks before or during sleep that wake you up? Just curious.
Hope you can find some answers. Good Luck
In the year 2000 I started having non-epileptic seizures after massive migraines. I was also jerking involuntarily all over different parts of my body. Nothing showed up on the EEG, but on the MRI I was diagnosed with severe Cerivcal Stenosis. The Neurosurgeon I spoke with said this "MAY" have caused the seizures, but he wasn't sure. My Nuerologist (who is the greatest by the way) gave me some anti-seizure medication and I've been doing pretty good so far. I'm being monitored constantly and there's been some real progress.
Anyway, I hope you can get some good care and find out what you have so you can get something to help you. Good luck.