Are Swab Tests To Check Presence Of STD Reliable?

HELLO - a boy I slept with a year ago has herpes and he got it from a girl he had slept with before me. I went and got tested - the doctor took a swab and a few weeks later called me back and said that I was in the clear. But I am reading up on it now and it seems the swabs will only come back positive if you have a break up? Should she have given me a blood test instead? Should I go back and get tested again?