Something crawling in my socks?

There seem to be bugs crawling around in my socks and sometime up my legs as I write this. They must be very small because I can't see them at all. I'm worried they might be bed bugs, but have had no bites. Yet I have had the same feeling something is crawling at me at night, usually starting with my feet. If I launder my sheets the night time feeling goes away for a night, but is back the next night. Washing my socks doesn't seem to help,and even if I put on a fresh pair the crawling feeling in the socks soon appears. Any idea what the likely culprit may be? Thank you.