How would i know if these bites are from fleas?

Flea bites.: Flea bites may be clustered into 3 itchy bumps that bleed & blanch (turn white) when you press on them. They tend to be found at skin folds (breast or groin) & folds of joints (ankle, knee, elbow, axilla). A rash may develop and swelling can occur as well as secondary infection from scratching. Sometime biopsy is needed to make an accurate diagnosis.