Hi, Welcome and thanks for posting your query to HCM. After reading your query it is too early to make a pin point diagnosis as you have not mentioned your age and side of appearance, even then we can make out two possibilities: 1. Herpes zoster: If the lesions are on the same side then there is possibility of this problem which is actually a viral infection by herpes virus causing unilateral appearance of blisters with pain in it. If you are young adult then this is not a thing of worry but if you are post 40 years then definitely need antiviral therapy. 2. Contact irritant/allergic dermatitis(CID):It appears due to contact with some allergic or irritant material. Though according to you have not done anything unusual so possibility is less. For the time being keep a watch over the lesions if they increase or become large in size or painful then you must consult a dermatologist who can prescribe you the treatment accordingly. Till that time you can do cold compressions for multiple times a day and can apply very thin layer of calamine lotion. Do not apply anything having irritant potential- and no self medications. Hope this information will be helpful. Dr Sanjay K Kanodia MD ( Dermatology and STD/ Venereology)