From the photo you submitted, both Herpes zoster (shingles) and folliculitis seem possible. Shingles is usually very painful and the lesions typically form small fluid filled blisters. Folliculitis, although sometimes tender, would typically be less painful at an early stage, and it might be itchy. Those historical clues might help you make further decide which diagnosis is more likely. Also, as the lesions evolve over a few days, sometimes the diagnosis becomes much clearer. In the mean time, I would recommend you apply a cortisone cream (such as 1% hydrocortisone cream over the counter) twice daily for 3-5 days to see if this helps. Folliculitis can sometimes be infectious, and if not improving in a few days, you should see a dermatologist to help sort this out and prevent progression.