My inguinal lymph nodes on both sides have been swollen for a year. blood tests last year showed nothing. what could it be & should i get more tests?

Probably nothing: As a kid and a young doctor, my groin nodes were always big especially in the summer from going barefoot. Yes, that'll do it. If they're not more than a few cm across, don't look like golf balls buried in there, aren't fixed firmly to the nearby structures, and aren't expecially tender or painful, and you don't feel sick, they're best ignored. What you describe is very common. Best wishes.