How can I tell if my platysma was injured/torn/separated from liposuction under the chin?

2 months ago I had submental liposuction from an incision placed under my chin. My platysma muscle is now bulging out, and I am experiencing a change in my ability to move my head due to pain and tugging of the muscle under my chin. My PS said it is a spasm, and tried botox. The botox did not help. I am a healthy 31 yr old female. I had no issue with this muscle before the surgery. The skin under my chin feels overly tight, don't want any tightening procedures, I want the opposite.