Swollen bite

Hi mummies. Wonder if any of you occur this before. My lo is having this kind of bite in the toddler group, at first is at the leg now happen on the hand too. It’s red and swollen and feels hot. Went to see doc before, taken the medicine and it’s fine for about a week, after that come back again. Is this common insect bite? Or some kind of bacteria? Should I bring her for a blood test? Thanks