Be sure the personnel or human resources department is told. Go to the doctor or hospital for examination, by ambulance if necessary. If you are able to continue working and are being treated differently on the job, document everything. If you are unable to work, your employer's disability, state disability, or workers compensation benefits usually start within 2 weeks. You may also be eligible for state disability benefits, so see your county's Human Services office.
Attorneys specialize in workers compensation.
You may want to hire one at any point in this process. The attorney is not paid unless you win. Read up on your state's workers compensation policy. Although the federal government requires certain benefits in all states, the states have the latitude to change other parts. Most state workers compensation laws can be found on the Internet.