Jar, sorry to hear you got slammed. Gotta watch them Prius drivers...
As far as the insurance offer, their job is to settle as cheap and as fast as possible before you lawyer up.
You probably should go back and get the pain med prescription. You dont even need to get it filled, just get it. (You just want a record on file that you needed it...)
Certainly tell the State Farm person that their offer is not acceptable and that you will have to discuss this with a legal representative first, as well as you don't want to consider it anyway as you will still be getting medical treatments it appears. Tell them you appreciate talking to them and then just end the call professionally and politely. They will call you back within a few days with a better offer.
Spoiler....