painless blisters on lower back and center chest

last week i found some small painless small blisters in the center of my chest,. This morning i found many more on my lower back, in the spine eara. What could cause this ?

[Dr. Kokil Mathur]

Hi
Welcome to the forum!
Blisters can be caused by intense rubbing or friction. They can also be seen in moist skin as one always covered with sweat or water. Blisters can also be a part of contact dermatitis like contact with soap, detergents, powder etc. Pemphigus and bullous pemphigoid are the other conditions that should be ruled out.
There are other causes of blisters too but probably they do not apply in your case. These are Dermatitis herpetiformis, chronic bullous dermatosis, cutaneous radiation syndrome (following a radiation--maybe for cancers or X-rays or CT scans), and Epidermolysis Bullosa.
Though painless shingles is rare, that is another possibility that cannot be completely ruled out. Chicken pox and poison ivy too cause blistering rash.
Please consult a skin specialist regarding this as a confirmed diagnosis cannot be given on net without examining the rash. You can discuss theses possibilities with the specialist.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!