Cluster of blisters very swollen and red. dark red/purple around edges very painful on calf anyone know what it could be? hospital unsure

Several causes: Shingles usually causes cluster(s) of tiny blisters (vesicles). If you have pain in a much wider area than is covered by the blisters, shingles is likely. The same is true if new clusters appear in the same general part of your body. Insect/spider bites are also possible. If the rash becomes more generalized, you may need one of these areas biopsied to get the diagnosis.