Significant redness and swelling around eyes

Owen woke up from his nap at day care with significant redness and swelling around the eyes. They were very itchy. I gave him .5 teaspoon of benadryl, and he seemed to get relief. Then during dinner, redness and hives developed again around the eyes. It had only been 3 hours since I gave him benadryl, but since he was symptomatic, I gave him another .5 teaspoon. The redness and swelling has gone down, but did not disappear.

I called Dr. Banks and he is concerned that it might be the new mulch that the daycare just put down in their playground. I sure hope it is not that.