Hives outbreak

What is so wrong with me? I am suffering from a serious Hives outbreak. It happened a couple of days ago in the evenings but got serious in the office the day before. I couldn't stop scratching myself & there were huge batches of red on my skin. Took a jab & felt much better, only to wake up to it again this morning!

I already changed the bedsheets & clothes but why still the itch?? Some say it's a change in temperature, others say dust but when i checked the internet, the cause - UNKNOWN.

This itch is driving me nuts. Can't scratch else kena scars. Don't scratch, itch killing... URGH!!!!