In 2004, when all the hurricanes were hitting Florida, a colony of fire ants decided to move into our apartment (this seems to be something they do when there is either too much or too little rain around here). It took us 4 months to get rid of them, the exterminator would not believe it was fire ants until we caught some and showed him.

They were eating into our food, showing up in the fridge, the cabinets, and in our beds. I woke up one morning with an itchy wrist and within a few hours it was swollen up quite large. When the swelling went down I had two pustules from fire ant stings. Shrugged that off (and went and complained again for them to get the guy out to spray), then two weeks later I woke up with another sting, this time on my neck. Within a few minutes my hands and feet were itching and burning like mad and starting to swell up. I took benadryl and it went away thankfully.

So yea, could be fire ants! I had one get me while I was on the bike about a month ago. I stopped about 30 minutes into the ride and stood in some grass for a bit. Must have gotten on me then, made it's way to my face over the course of the next 45 minutes, and stung me on my tongue (of all places!) when I felt something on my lip and instinctively licked it.

I think for the most part stuff will leave you alone even once it is on you unless it decides it is threatened. Maybe it was a spider and it did not feel threatened until then?