I'm Thinking I May Have Starting Stages Of Shingles. I

I'm thinking I may have starting stages of Shingles. I have small blisters under one breast and on side flank. I thought it was a heat rash but it is painful and triggers a sharp stabbing pain. I have also got a couple small blisters on my back mid waist which looked like spider bite or pimple, that area is also tender and another sometime painful spot on upper back but I don't see any blistering. I have applied cortisone cream, and other topical creams with no success.