A man consults a physician with complaints of cramping pain in left side of the chest, general weakness, fever and headache that have appeared 2 days ago. This morning the patient noticed a skin rash on the chest. Physical examination: multiple aggregated vesicles with edematous covers filled with transparent liquid, 2-4 mm in diameter. Vesicles are situated on the erythematous and edematous background along 4-5 intercostals. What is the most likely diagnosis?