Does anyone know what these are ?


I noticed the first two on my thigh yesterday , they felt like big lumps but the middle of them feels like it dips down & they're extremely itchy. Today, two more identical ones have come up on the inside of my leg & on my arm , they're bigger & itchier. I was thinking they're bites but no one else in my house has them , my boyfriend shares a bed with me & he's fine so I can't understand what could have bitten me. Does anyone know what they are ?