Allergy on something I didn’t know

My kid and I went to the grocery at noon time to buy few fruits, vegetables, and meat. I had fun choosing the goodies that I needed to buy but then when I tried to look at him inside the kiddy push cart which was attached to the grocery shopping cart, oh my, he’s mouth and his face was reddish in color.It means he’s allergy to something I didn’t know. So no choice I had to find the bathroom. When we got there, I opened the door because it’s not lock. To my surprise, there was an old woman who’s doing her bathroom duties. So I closed the door and waited for several minutes. After that woman was out, I hurriedly washed the hands of my kid and his face. I didn’t let him get inside the kiddie push cart again coz I was worried if she will be having another allergy reaction and I didn’t bring any epi-pen or Benadryl with me. Sigh, I was paranoid and it resulted that I forgot to buy the goodies on my list.