There are several causes of a blistering rash, but the most common cause of a blistering rash in clusters that also burns is zoster. This is a viral infection caused by the same virus as chicken pox, and presents with blisters that cluster on one half of the body and can cause severe burning pain. There is an antiviral treatment for this infection that can speed the healing of the skin lesions and the resolution of pain, so I would strongly recommend seeing a doctor
to discuss whether this is actually zoster and whether you would benefit from the antiviral treatment.
Other possibilities for a blistering rash include different kinds of allergic reaction, ranging from contact dermatitis or eczema
, to a systemic drug reaction called erythema multiforme. Infectious causes of a blistering skin rash besides zoster includes herpes simplex, impetigo, or a shock reaction to a bacterial infection. There are also autoimmune diseases that can cause blistering, including bullous pemphigoid and pemphigus vulgaris, and celiac's disease can have a blistering skin component called dermatitis herpetiformis. You can also develop blisters simply from friction which could be due to your pants or belt. Because the list of possibilities is so broad I would definitely recommend taking a picture of the rash now and trying to see your primary care doctor
as soon as possible so they can assess what might be going on.