I got a chin implant and neck liposuction 7 weeks ago. Three weeks after my surgery I started noticing this vertical band appear on my neck. I went back to see my PS and he said it was my platysmal muscle having a spasm. It's tender when I push on it, and it's very tight when I extend my neck back. He injected it with 20 units of botox 7 days ago. I still see no change? Could it be the dose is to low? What can I do ?