Have your windows been open recently? I went camping a month ago and these darn little gnats were so small they went through the mesh on the tent and made sleeping every night impossible for me because they wouldn't stop biting me. It made me so paranoid that I started to feel itchy all over so I would hide under my sleeping bag at night.
Those are called "No-See-Ums".....very scientific name there huh? We have friends who drive down to FL every Feb. and camp at several different places for 2 - 3 weeks. They have shared some horror stories about the No-See-Ums, and they are so small you cannot really keep them out of anything, screens and mosquito netting don't work.