I received a tetanus shot on tuesday. last night i couldn't sleep because my entire arm and hand were throbbing with pain? what's going on?

Shot reaction: This is not an uncommon reaction to a vaccine. Checking the blood for immunity to a specific vaccine is a good idea before getting another one. Once a reaction occurs, the next time could cause a worse reaction.

Probably nothing : Most likely is a local reaction to the inoculation. However, if things persist longer than 48-72 hours then seek medical attention