What Does Red Spots On The Upper Calf Indicate?

I am seeing a half circle (about dime-size) of red dots, and perhaps 1 or 2 central dots. This appeared on the upper calf, at the inside of my left leg; no itching or insect present. I was visiting Fort Collins, Colorado; had taken car ride to Rocky Mountain National Park, walked a bit around rocks and gift shops. Also, walked through Colorado State University flower garden in evening (experimental varieties of common flowers); weather: cool with occasional sprinkles, grass ankle high. Still wearing hiking shoes and socks, long sturdy pants with stove pipe (loose) legs from the day. First observed above pattern at bed-time/within 2-3 hours; continues 10 days later. May experience passing heat or rash on legs lasting from minutes to an hour.