Unfortunately, popping it means that if they cultured it, the test might not be accurate.
A chancre is a syphilis sore, not a herpes sore, and that's a round, open, painless sore - not something you'd be able to pop.
What is the timeline here? How long after the oral did you get the inflamed gland and sore?
Have you ever had a cold sore or know if you have oral hsv1? What kind of testing did you get done?