What you are describing could also be shingles if you had chicken pox as a child. Exposure in adulthood to the virus again can reactivate it in yourself but it comes out as shingles. The fluid in the shingles blister is contagious and can cause chicken pox in the kids if they touch it. A clinic or doctor's visit would be a good idea to get a diagnosis and if you do it immediately after exposure there are medicines that can lesson the severity.