Sulfur, for sure, Walt. We just haven't got around to fumigating the house, yet. Too busy with life on the "farm". Not to mention it's quite a scary process.
Unfortunately, TT, there are two types of bird mites (if that's what I've got) in North America and one is almost invisible to the naked eye. It's called Dermanyssus gallinae Also, they don't hop and fly. They crawl. Several times, I have put my finger on what felt like a hard little bug at the exact site of a bite. One of these I wrapped up well in tinfoil and was planning to take it to the vet. But the little s.o.b. exited, something they are very good at. They really have to be caught on tape (sticky tape, lol) to be identified.
As to the finger nail bite, I saw a similar "something". My husband has since started using a tiny microscope with a bright light on it. We've seen some weird stuff but not an actual mite. At this point, I only think the problem is bird mites because the description (sharp pinpricks and crawling sensations) fits and so does the fact that they are far more active at night. There are other possibilities, of course. One is little critters who live in hay and cause Itchy Farmers Everywhere Syndrome (IFES).

Just kidding, not about the hay critters, though. In brief, I don't really care what they're called although if I ever catch one I'll attempt to get it identified because different bugs respond to different treatments, obviously.
I've NEVER felt this buggy in my life so I actually don't think a delusional parasitosis diagnosis makes sense. Could be, of course, but ordinary TMS seems more likely and thinking it's TMS has helped to calm me down. I am no longer having much reaction to the bites but I do have to take something to sleep. When I woke up this morning, the feeling of having bugs on me was intense. I got up, showered and scrubbed off and felt good all day. Hardly an itch. As soon as we got home, though, it started up a bit.
I also don't think my problem is
just TMS but with me TMS is always lurking ready to exacerbate the situation especially when I am tired and upset. I hope to avoid the extremes some folks go to get rid of bugs. It can get pretty crazy and is a heck of a lot of work:
http://yearofthemite.com/2012/05/27/welcome-to-year-of-the-mite/
We have booted the chickens back into their coop (no more free ranging) so they can't hang around our main door. Presumably the bird mites (if that's what they are) will follow them. It seemed to help for awhile although this super hot, occasionally humid, weather is not good. Most sites online say the mites can't reproduce on human blood but, sadly, I've found an expert in the UK who says they certainly can. Still, they prefer birds. So, I'm hoping they'll go bird hunting, eventually.
North Star, everyone I know feels itchy when I tell them. I'm scared to visit them (in their homes, especially) because I don't want them to go through this.