Can the insurance company use my Facebook posts against me?
You need to be careful with what you post on Facebook if you are pursuing an injury claim. The reason is the insurance company, their attorneys and their adjusters can possibly access this information and whatever you post can and will be used against you. Somehow, some way, the insurance company can twist your Facebook activity to make it look like you're not as hurt as you say you are.
If you are pursuing an injury claim, make your Facebook settings private so the insurance company can't have easy access to it. More importantly - watch what you post on Facebook, because whatever you post can be twisted and turned and used against you.