anyone have a LO with a peanut allergy?

How did you first know?  Jake has had some small exposure to peanuts but has never really been interested in peanut butter.  Tonight he had a little of Matt's Reese's cup and then had red splotches develop on his cheeks.  They went away after an hour.

Since I live on peanuts, I am fearing the worst.  I am also wondering what smart next steps are. Will a doctor think I am crazy if I ask to get him tested?  I am thinking with peanuts the next exposure might be a stronger reaction, so I don't know if "wait and see" is the best course.