Fire Ants

We've had our first big fire ant attic. John's little foot is covered in dozens of bites (I want to say hundreds but that would be exaggerating). it just seems like hundreds with him screaming and how much cortisone was applied. We had arrived home from doing a quick banking trip, John had spilled yogurt in the van and on his leg and foot. I set him on the ground and urged him to go inside the house while I got the mess cleaned up. He got distracted with his tricycle and the next thing I knew he is screaming saying his 'bike hurt him'. I'm thinking he scraped his foot on the pavement. I looked and it was red but I didn't see anything, no ants, no blood. I remember him trying to get me to kiss it and I said I would blow a kiss because his feet were too dirty!
About an hour later he is crying and I see welts covering his entire foot and up his ankle. Poor little guy. It was then he told me about the ants. I don't remember him saying anything about ants. But something could have been lost in the screaming.