My Budgie's Legs Are Constantly Twitching

[TashLeeJoe 0]

Hi, 

For some time now my budgie's legs are constantly twitching. Even when he is asleep this is happening. We read online that a diet of only seeds could cause this, so we got him off the seeds and on to pellets. He's been 2 weeks on pellets only with no change in the leg twitching. The twitching happens no matter what surface he is on, so it's not due to the perch. Happens when he's on top the cage, on my shoulder etc. 

Here is a short video showing the movement. 

Any advice? It's really distressing, and he's constantly tired since I don't think he's able to sleep as a result.