Red spots on bottom of foot?

DS had a fever starting Thursday 5/15. Went to dr, he had a red throat (no strep), ears fine, figured it was a mystery virus. Fever broke that Sunday night but we went back in Monday bc he was still not himself and dr said ear infection so he's on meds for that. Around that time I had noticed what looked like a mosquito bite in a couple places on his one foot. Well now, almost a week later, they're still there and more pronounced. They're raised slightly but he doesn't seem bothered by them even when I touch them. They just look bad! I'm wondering if the fever may have been the beginning of HFM -- and if so can kids get the spots only on their feet? (One foot??) He's had 2 drs look in his mouth recently and I'm assuming they would have told me if they noticed spots! I don't see them anywhere else. And if it's not HFM any idea what it could be? I'm not rushing to call the dr on this since if it IS HFM there isn't really anything to do for him. Unless it starts bothering him or looks much worse we will just wait it out.