Hello. My name is Marc. I'm a licensed attorney and I will be happy to assist you today? First of all, it's good news that you have returned to work, and I hope you have recovered from your injury or illness. Unfortunately, however unfair your employer's treatment is, the initial impression here is that your employer's action did not run afoul of CA or federal laws pertaining to disability leave.
As an initial matter, I will assume that your employer has 50 or more employees, in which case the CA and federal laws apply. If under 50 employees, then you are not protected from your employer's negative actions based on your medial leave.
The CA and federal laws are very similar when it comes to who is protected and for how long. Basically, you are permitted to take unpaid leave for up to total of 12 weeks during a 12-month period for, among other things, a serious health condition. This includes illness, injury, impairment, or physical or mental condition involving incapacity or treatment connected with inpatient care in hospital, hospice, or residential medical-care facility; or, continuing treatment by a health care provider involving a period of incapacity: (1) requiring absence of more than 3 consecutive calendar days from work, school, or other activities; (2) due to a chronic or long-term condition for which treatment may be ineffective; (3) absences to receive multiple treatments (including recovery periods) for a condition that if left untreated likely would result in incapacity of more than 3 days; or (4) due to any incapacity related to pregnancy or for prenatal care.
Your illness or injury that required you to remain out on leave for 7 months most likely would qualify as a covered serious illness. But, the 7-month period clearly exceeds the 12-week period that is protected under the law. Therefore, assuming your condition is not related to a work-related accident, you were not protected from any related adverse employment action. Furthermore, although a poor performance review can technically be considered an adverse employment action that would be proscribed, that is typically much more difficult to allege compared to termination or demotion, for example.
In sum, and without knowing all the precise details, it is likely that your employer's negative PER based on excessive absences is legal. Keep in mind, however, that you are entitled to discuss the issue privately with your HR department. Having done so, your employer will absolutely be prohibited from taking any retaliatory action against you for inquiring into or asserting your rights under the Family Medical Leave Act. Of course, this is something to consider if you work for a larger company, which has a formal HR department and an established policy - not if you work for a small organization, wherein there often are weak policies or none at all.
I know this may not be as optimistic an answer as you might have been hoping for. But I hope I have provided useful information that helps you better understand your issues and options. If so, please feel free to rate my answer, as that is the only way I can receive credit.
Meanwhile, I wish you health and prosperity at work and beyond.