I Have What Appear To Be Bug Bites, But There

I have what appear to be bug bites, but there no bugs around. There come on randomly on different parts of my body. They are itchy, do not bleed. I get them on my head where I find a bump and a hard, crystallized, clear substance. They come up sometimes in the middle of the day on my arms and legs. I do not take any medications and live a clean, healthy lifestyle. Symptoms started about six months ago when we moved from CO to OR.