Could just a bump lead to herpes?

Herpes simplex: Yes. Herpetic eruptions can present initially as a small "bump" but quickly become a vesicle (blister) and then open and form a shallow very painful and tender ulcer.

The other way: If you have herpes, it can lead to burning, pain, numbness, tingling, itching, and rash that can include a bump or many bumps. They may occur in the boxers shorts area if it is type ii herpes simplex, and occur during times of physical or mental stress. Treatment is with Valtrex (valacyclovir) to shorten and ease the intensity of outbreaks. If this is not herpes, then a skin bump may just be a blemish or pimple.