The main thing was the alleged refusal to cut out and/or drain a fatty deposit that turned out to be a staph infection. There were also claims of improper concussion treatments and diagnoses and generally behaving in a manner that suited WWE opposed to the talent and their medical issues and concerns. That is a very serious charge and one that Punk made very loudly as the lawsuit points out.
In the DOT NET post on the matter I read it was stated this way.
Amann alleges that Colton helped Brooks falsely depict him as a lazy and bad doctor, and that both men "knowingly fabricated the false and disparaging statements."It takes a lot to surprise me, but I did not anticipate Dr. Amann firing back in a manner like this. It will be very interesting to see what, if anything, comes of this.