What causes Rosacea in babies?

My 8 month old went to doctor for his follow up due to emergency room visits Sunday twice. The er doctor diagnosed my son with double ear infections in each ear and gave him amoxcilion for 10 days. His pediatrician looked at his ears yesterday at his appointment and said he didn't have red ears but could had it within 24 hours but did blood work that came back Rosacea. He said he will break out in welps.. How does babies get this and how to treat it? Doctor didn't say yesterday other than to continue his amoxicillin.