Does she have syphilis

I was going down on this girl and noticed she had a single white ulcer on her vagina lips. When I asked her about it, she said she never noticed until I mentioned it. She said the ulcer is painless but she is still going to get a STD check today. The ulcer looks like the link below but on her vagina.
https://goo.gl/BIuwpX
Should I be worried about syphilis? Would it be better if she went to her gynecologist instead? STD checks are quite expensive here.