A blood test can be used to test for herpes antibodies... although these tests often aren't done because they are expensive, most insurance wont cover them, and a very large percentage of the population will test positive for HSV 1.

Also, OP, symptoms for herpes can show up a long time after exposure. I know mine did. Your best bet would be to head to the doctor, have them examine you, and possibly culture the sore. My first outbreak came complete with the flu like symptoms that you are describing.