The crystals or crunchy bits that you're referring to is the protein in the cheese crystalizing. When this happens you've got one hell of a piece of cheese. You can get great crystal formation with great Parm, I once had a piece of 10yr aged Parm that was full of these crystals. Rembrant Gouda is also one of the great examples of this crystal formation. This cheese that your talking about sound like a very aged Piave Stravecchio, which translates to extra old. The flavor once this cheese is aged is very intense. I'm still not sure what was causing the blisters to form, unless it was some type of allergic reaction.