I work in HR and I've seen this happen with managers before. Once a manager decides they don't want to have someone working with them for *whatever reason*, they will start documenting all the little things that they normally wouldn't care about in order to build a case for a termination. Unfortunately, there is nothing legally to prevent them from doing this. Document as much of this experience as you possibly can, especially if you intend to file for unemployment. In circumstances like this, I definitely recommend waiting for them to let you go. It will help your case in the unemployment process and puts them in a defensive position if you do proceed with a lawsuit.

Good luck!