Allergies?

I suffer from a whole lot of different allergies.  No strange allergies really, just the typical hay fever, pollen, dust, etc.  I am also allergic to cats.  I don't think my husband is allergic to anything.  Obviously I had hoped that Superman would take after his father and not be an allergic to anything.  Yeah, I don't think we are going to be that lucky.

We were at our playgroup date today and the host had a cat.  I have learned that as long as I don't pet the cat and wash my hands when I leave, I can avoid a lot of the symptoms so I didn't have a problem at all today.  Superman on the other hand seemed to have a reaction.

First his nose was running a little bit more than it has been and then he began to cough.  I assumed it was due to the runny nose and it may have still been because of that, but as we left the house he began to cough even more.  Five minutes into our drive he was really coughing...a bad barking type cough.  I started to really worry that he was sick and I had just exposed several kids to this unknown illness.  I figured I would watch his symptoms and make some phone calls tonight to the other moms if he got worse. 

Instead?  He got better.  Almost completely better.  He still had a little bit of a cough this evening, but it was just a small light cough, not the hacking barking cough from earlier in the afternoon.  Also he has been in bed now for almost 30 minutes and hasn't coughed once. 

So I am assuming it was an allergy attack.  Is that the conclusion you would come to?  Maybe I am jumping the gun that it was the cat that he was allergic to...he didn't really get worse till we left, but that sometimes happens to me if I don't spend a really long time at the home.    I am 99% sure it wasn't anything in the new car because we had already driven in it for about 2 hours without a reaction.

So now the question is, what do we do with this information?  Is there allergy medication for toddlers?  If there is, is there a downside (or side effects) to medicating him?  We are going to stay with my sister in a couple weeks and I always struggle with my allergies when I visit.  What will we do with Superman if he starts with the barking cough again?  Anyone have any experience with this?  Help!