Son has been in daycare for a year now, will the constant runny nose and back-to-back viruses ever stop?

Our pediatrician told us to be prepared for him and us to pretty much be sick all the time for the first 6 months - 1 year of him being in day care. He just got done with a round of antibiotics for a pretty bad ear and eye infection and he also developed thrush during that time and was having a reaction to the thrush medication. It was a nightmare. But everything cleared up and he was good for about a week and now this morning he has a bad mucusy cough and a runny nose (yellow snot) again. It's so frustrating! He's almost 3. I feel bad that he is congested literally all the time. I know that his immune system is being built up and all of that but is there light at the end of the tunnel? Also, I'm wondering could allergies be the culprit? We do have cats and a dog. via /r/Parenting http://ift.tt/2oxG4cC