The original blisters sounded like a bacterial infection, but what's happened since doesn't fit that. I don't know whether you've seen a dermatologist yet, but you should. Skin cultures for bacteria and fungi meed to be done. Some forms of (non-infectious) eczema can also behave in this way. This doesn't sound serious, but does need personal attention, testing and trials of treatment.
Best.
Dr. Rockoff