hello and thanks for the query .
as u have mentioned in ur question that the nail was rusted, hence there is a high chance of developing secondary infection due to tetanus
or other organism. since u can't remember the exact time of vaccination
it wud be advisable to get a booster dose of tetanus again. also u must get yourself clinically examined by a doctor since u may require surgical debridement and sutures with appropriate dressing of the wound. it wud be advisable to start a course of oral antibiotic since ur wound show redness
and may already be infected. I wud advice u visit ur nearest doctor as soon as possible since the infection can spread very fast.
hopefully this will solve ur problem.