For how long have you noted these?
Acne usually affect the
chest, back and of course the face, however, it is important to rule out other skin conditions here. I suggest that you have your linens and clothes checked. Also, if other triggers such as prolonged sun exposure, dust and certain food may be associated with this, then it is best to avoid these also.
Rosacea may also be considered especially if the rash appears red and the skin appears thick.