You need to immediately contact an employment attorney in your area. Patrick John Phillips comes to mind as being an experienced attorney on these matters in San Diego. While you may believe the initial performance improvement plan was bogus, the employer may not see it that way and has wide discretion regarding at-will employees.
However, if you were injured on the job, your employer must seek to accommodate your injury and engage in the interactive process. While they may claim to be accommodating you by letting you come in for work, you may be correct that they will use this time against your performance improvement plan as a means for terminating you.
First, if you don't have a workers' compensation attorney, get one right away. Don't rely on the company's workers' compensation department to take care of you. The company's workers' compensation staff is there to protect the company, not you. You can find a workers' compensation attorney on the California Applicant Attorneys Association (CAAA) web site: http://caaa.org/cs/. CAAA is the strongest California bar association for attorneys who represent injured workers. On the home page, click on the picture of the wheelchair above the words "Injured Workers." On the next page, click on the link to “Attorney Search” on the left side. Enter your city or any other information and click “Search.”
Most likely you have a serious medical condition as defined by one of the family leave acts – FMLA or the California Family Rights Act (CFRA). If so, then you may be entitled to up to up to 12 weeks of unpaid leave from work, without penalty. Leave can be in increments as short as fractions of an hourThe FMLA and CFRA apply if all of the following is true: (a) your employer has at least 50 employees who work within 75 miles of one another; and (b) you have worked for this employer for at least one year all together, even if not consecutively; (c) you have worked for this employer at least 1,250 hours in the immediately preceding year; and (d) you have, or a spouse, parent or child has, a serious medical condition as defined by the FMLA. Please look at my Avvo guide on the Family and Medical Leave Act, 29 U.S.C. section 2101 et seq. (FMLA): http://www.avvo.com/pages/show?category_id=6&permalink=family-and-medical-leave-fmla-summary-of-key-provisions.
These family leave laws make it illegal for an employer to retaliate or discriminate against an employee who qualifies for family leave. Holding such an employee to the same standards as an employee without the need for family leave is against the law.
If your injury meets the definition of "disability" under the California Fair Employment and Housing Act, you have substantial additional protection. Please look at my Avvo guide on the ADA: http://www.avvo.com/pages/show?category_id=6&permalink=disability-discrimination-in-employment. Please look at my Avvo guide to the differences between the ADA and California's more generous FEHA: http://www.avvo.com/legal-guides/ugc/employment-disability-protection-under-californias-fair-employment-and-housing-act-and-federal-ada?published=true.
It may be a violation of Labor Code 132a to effectively require you to perform as if you were not injured. This workers' compensation statute prohibits discrimination and retaliation against employees who are injured on the job. The law is usually applied differently, but I can see an argument to apply it to your situation.
Employment law is complicated and fact-specific. You may wish to consult with an experienced plaintiffs employment lawyer. To find a plaintiffs employment attorney in California, please go to the web site of the California Employment Lawyers Association (CELA). CELA is the largest and most influential bar association in the state for attorneys who represent working people. The web site is www.cela.org. Click on "Find a CELA Member" and you can search by location and practice area. Many CELA attorneys represent clients throughout the state.
I hope you can resolve your situation and wish you the best.
@MikaSpencer * * * twitter.com/MikaSpencer * * * PLEASE READ: All legal actions have time limits, called statutes of limitation. If you miss the deadline for filing your claim, you will lose the opportunity to pursue your case. Please consult with an experienced employment attorney as soon as possible to better preserve your rights. * * * Marilynn Mika Spencer provides information on Avvo as a service to the public, primarily when general information may be of assistance. Avvo is not an appropriate forum for an in-depth response or a detailed analysis. These comments are for information only and should not be considered legal advice. Legal advice must pertain to specific, detailed facts. * * * No attorney-client relationship is created based on this information exchange. * * * Marilynn Mika Spencer is licensed to practice law before all state and federal courts in California and can appear before administrative agencies throughout the country. She is eligible to represent clients in other states on a pro hac vice basis.