What causes random mosquito-looking bumps on a person, they itch worse than anything imaginable?

For the past 7 weeks, mosquito-looking bites have popped up all over me, ranging from my feet to my elbows, to my back, my neck, etc. I have been to 4 different doctors and at first I was told they were mosquito bites, then maybe scabies(which I knew it definately wasnt) and then recently, eczema. I know what eczema is and what I have is not eczema. It looks like mosquito bites that can be as big as my thumbnail! The itch like crazy and stay for like a week, then go away and reappear somewhere else. If anyone has any clue what this could be, it would be reallly appreciative since 4 doctors cannot reach a consensus on what it is. Thanks!