What causes red blotchy spots under your breasts and on your stomach?

I am not exactly sure what might cause this. I do know however, that I got them after becoming pregnant, and I have been told that they should go away eventually after the baby is born.

Answer

I am 56 years old, fair skined and I have noticed blotches that appear on my breasts and tummy whenever my body is fighting something, usually an infection. I may have a low grade fever before or during. I have seen a GP and a dermatologist, when I am in the midst of one of these attacks and they seem to concur with my guess, as they can find no other reason for the blotches. They disappear in a few days when I am well again.

If you are bigger, it could just be heat rash. I get that sometimes.