I have red bumps all over my Body various sizes

I had them for about a month now, I'm not sure why , also they itch. i been to the doctors and they do not know. i been using moisturizers to prevent dry skin. Its been getting worse. Some spots became a different color, darker than my skin. I hope they don't scar. They are all various different sizes. Any idea's? any help is greatly appreciated. I haven't gotten them on my face, neck, hands, fingers, toes, wrist and genitals. Also can an allergic reaction break days later after eating something, instead of happening withing minutes? i never really notice if i was ever allergic to anything, my mum and dad aren't allergic to anything. my doctor doesn't think its scabies or bed bugs or eczema or sti, I need help!