What Causes Rashes On Stomach, Back, Thigh And Chest?

I have a rash mostly on my belly, some on my back and one spot each on my thigh and chest. These are reddish spots, some slightly raised and itchy at times. I am peri-menopausal - almost at menopause - have not had a period in the last two months, but was regular until then. I am 50yrs old, height is 5.6' and weight is 145 lbs.