Quick background summary - I've been with my employer for 5 years. The first 4 I was recognised as a high performer each year. Just over a year ago I had a severe mental breakdown (hospital for 4 weeks then off for another 8) Returned to work and boss has changed from good work mate to total superbitch. After trying to pin her down over several months and getting crap answers from her, we have a meeting where I tell her that the way she is behaving is making me ill and I want to resign. She asks me not to and that all is fine. Go on holiday and when I get back she's sent me an invite to discuss performance concerns and once I'm there she tells me I'm now on a performance improvement plan. I suffer a complete relapse.
What I need to know is, is there a general approach to how and when a company puts someone on a PIP? How common is it where no performance concerns have been previously raised with an employee? If HR approve the PIP, what do they consider before giving approval?
If anyone can help I would be soooo grateful!