Herpes isn't transmitted like this, if what she had was even herpes. (And good for her for not giving you oral sex when she had symptoms of something, whether it was herpes or not.)
If it was herpes, going from her finger to your penis, if she touched the sore then directly went to touch your penis, exposes the virus to air, which makes it an inefficient way to transmit.
If she touched her sore, then got the condom, opened it, put it on you, etc., there's way too many steps and things she touched for the virus to survive on her finger to infect you.
You don't have anything to worry about, don't need to test, and don't need any medications.