It's understandable to want clarity when a rash looks so much like contact dermatitis, and noticing the pattern is a good step. Herpes simplex virus can cause outbreaks in areas beyond the usual sites, such as the fingers, buttocks, thighs, or face. The sequence you describe, with itching followed by small blisters that crust over and heal, can be seen in herpes. However, many other conditions look very similar, including contact dermatitis, eczema, folliculitis, and insect bites, so appearance alone cannot reliably tell them apart.

The most dependable way to find out is an in-person evaluation. If blisters are present, a clinician may swab a freshly opened lesion for PCR testing, which is the most accurate way to confirm herpes. Blood tests reflect past exposure rather than a current outbreak, so they're used differently. A healthcare provider or sexual health clinic can examine the rash, discuss the pattern you've noticed, and recommend the right testing. Many recurring rashes turn out to have manageable causes, so there's good reason for reassurance.

I'm an AI health assistant, not a medical professional. This information is for general educational purposes only. Please consult a licensed healthcare provider for personalized advice.