Hello,
These blisters can be due to insect bite or contact dermatitis. Try keeping the skin free of sweat as far as possible and do not wear any socks. For the itching antihistaminics like Benadryl or Claritin can be taken.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
If Vick's vap o rub cures it, it is athlelte's foot.