This could be herpes zoster
infection. This is a viral infection which occurs in a particular area according to the nerve distribution in the body. This is called as dermatomes.This infection presents as small red blisters
which are very itchy and painful. It is also associated with pain and tingling sensations in the limb involved. Local application of acyclovir
cream 4-5 times a day on the rashes and consult your doctor for antiviral
therapy. Do not delay the consultation.