They may be reddish or brown and are mainly seen on the arms and legs. Seborrheic dermatitis is a type of eczema that usually affects the scalp. Nummular eczema tends to cause numerous rashes.

Jamie Samnang, 41, thought she'd been bitten by a mosquito during her gym session when an itchy rash appeared ... It spread to my legs and ankles because I was itching my arms and then touching ...