What can you do about uneven neck muscles? (Photo)

Recently, I've noticed that my neck/shoulder muscles are uneven. It's not a huge difference, but my right side looks longer than my left because the muscles are higher. I have a short neck to begin with, so I would like to get as much length as possible. I read that you can use Botox to block muscles in the calves, so I was wondering if the same technique could be applied here. Stretches haven't really done anything. Also, would my neck look even shorter if I were to get a chin implant?