Do you have an ulcer on your genitalia? If not then the possibilities of Chancroid
are really low. But a tender lymph node can either be due to herpes or Chancroid. Doxycycline and Metronidazole
are not the correct choices for a tender inguinal node. I suggest you take Inj Ceftriaxone
1gm stat intramuscularly if the node is still very tender and you have a genital ulcer
. Regarding Herpes, there is no good test which firmly establishes the diagnosis. Clinical judgement is often the best and laboratory tests are only supplementary.