Recurring Bite Marks With Tiny Blisters Leaving Large, Raw Wound On Calf. Feeling Of Feverish, Unwell And Tired. Help

I have been suffering from a mystery skin condition which has reoccurred 4 times in the last two months. It always starts looking like a bad reaction to a "bite" and has always been on my legs. The skin around the "bites" becomes extremely painful and swollen. Tiny blisters appear at the site of the "bites" and within two weeks they calm down. The most recent occurrence caused two very large blisters on my calf which a doctor had to burst. The skin under the blister became infected, so I was given strong antibiotics. It has left a large wound on my calf which is very raw and is now going red/black. I have seen 4 different doctors but they do not know what the problem is. One doctor said bites, another said shingles and another suggested bullous. I have been feeling unwell, tired and very shivery/feverish. Please help.