I stepped on a rusty nail today that punctured my foot the puncture site is throbbing. do i need to go to doctor? my last tetnus shot was in 2008?

Close Observation: That nail went through many layers of tissue and each layer heals at a different rate. Skin heals quickly, the deep tough connective tissues takes a lot longer. Minimize strenuous activity for at least a week and progress slowly. There is no way to prevent infection so forget antibiotics. Observe and get help for fevers, increasing redness/drainage/pain. Your tetanus is ok for 5 more years.