Oh if it was 3 weeks post exposure, then yes you need to be tested again.
If the rash is new - within 24-48 hours of it appearing - you should get it cultured.
Aj
My first post is somewhat unclear, the test was 3 weeks post possible infection, sorry.
The rash was there for a week but is now gone, it came about 2 weeks post possible infection.
A rash that has been there this long is definitely not herpes!! You wasted money on an HSV test if you had a rash that wouldn't go away!! Your tests are accurate, you do NOT have herpes....