This is actually pretty common in Silkies, especially the ones with vaults (the big bumps on their head), because of the way their skulls form. They have a soft spot, much like a human babies head. They can get the wobbles from taking a peck there or hitting their heads on something. The recommended treatment is vitamin E and selenium or Poly-vi-Sol (baby vitamins) without iron, treatment may help but it may not completely cure it. My rooster wobbles, he always has, and he still manages his normal rooster duties.
My chicks also got the wobbles when I would feed medicated chick starter. The cocci medication works by blocking thiamine uptake, which starves the cocci protozoa. Thiamine (vitamin B1) is essential to all living things. Its absence can bring about detrimental neurological issues, like head wobble, flipping and head tucking. Thiamine deficiency can be fatal if left untreated. Simply changing to unmedicatd chick starter (if you're using it) will probably make a world of difference.
Good luck, I hope your chick is feeling better soon!