Hello I have an issue and need an advice. Some blisters appeared on my leg. At first there was a rash and a slight pain. Two hours later a couple of blisters appeared. The area is not burned, no trauma, as well. I had similar blisters appearing as a baby but the doctors then weren't able to diagnose them. As a baby they were appearing with a rash, lasted a couple of days and then burst. They were appearing for months and then disappeared completely until now (I am now 26) I am not taking any medications at the moment, I don't have any known allergies, haven't used new socks or shoes recently. I got a flu vaccine a month ago, if that's relevant. I went to a dermatologist but she also didn't know what that could be. She wanted to do a biopsy but I am afraid that they will pop until the sample can be taken. Can you please advise what might be the cause for these blisters?