What Causes A Swollen Itchy Rash On My Wrist?

i have a rash on my wrist which is a bit swollen, and hot to touch and slightly itchy, it looks like a bite or an allergic reaction to a bite or something, but it has occurred in the same place on my wrist 3 times now. At first I thought it was an allergic reation to my watch so I stopped wearing it. But the rash appeared again