Constant recurring red splotches on arms

Https://i.redditmedia.com/Amo2lOYLP2iGYXzBpvWRfKhOQ4SB6kjZtSoy-p581TA.jpg?w=432&s=f1f16825d Hi! I'm a 27 year old male living in Seattle as a software engineer that is 6'1 and weight ~200lbs, I keep getting these recurrent red marks on both my forearms, for months (6+) and it's really concerning me. I've been STD tested, and all came back negative, but these marks won't go away. What are they? Should I be as concerned as I am? I did have what I was told was eczema on my both my big toes a year ago, and it went away with a medium duty steriod cream and now daily application (just on the big toes) of petroleum jelly. I have confirmed allergies to dust mites, but I go to some pretty extrodinary lengths to limit exposure, and the allergist didn't seem to think my allergy was extreme (I wash my sheets in extreamly hot water twice a week, use a dust mite vacuum on all furniture, including bedding and pillows). I tried lamisil without any effect from doctor recommendation Thanks for any help!