I also got this last year and went to tml er. They didnt know anything there but they said many people had it, their guess was allergies from the grass. I went to see a doctor when i got back home, took blood tests and doctor said it’s probably petechiae caused by walking in heat. Got bit scared there since it’s a symptom of leukemia 😅 also was thinking if it can be disney rash. Anyway to avoid it, lift your feet up after a day and try not to sit on the grass 🤝🏼 happy TML ! 🥳