I wasn't sure if this should go in here, allergies, breastfeeding help or where?

Anyway.

I had some cashews the other day and fed DS a while afterwards. He came out in a fiery rash across his chin and cheeks. It was like someone had left him out in the sun! It looks soo angry.
It hung around for a few hours and disappeared.

Do you think it was the nuts? Coincidence? The cashews where the only thing I'd eaten for hours.