You are most likely dealing with Black flies..
They are slightly larger than gnats..
When they bite you they just chew until you bleed..
They have a anti-coagulant in their saliva which keeps the blood flowing..
Your body is having a reaction to the saliva which causes itching and swelling..
Not much you can do after they bite..
Use skeeter repellent to keep them at bay around your ears, neck and any clothing openings as they will crawl up your sleeves and pant legs..
I use to work in the Fort Nelson area up off of road 77 and they were bad this time of the year..
Really enjoying your ride commentary and photo's..