I've had this weird sensation for ages now and it's hard to explain so I've never really bothered before!
I can often feel what I think is running liquid on my skin, as if I've spilt water on myself but when I feel or look- nothing! It happens on different parts of me but mostly my legs.
I've also had the feeling of a bee or wasp on my skin, a sort of 'buzz' and I've been utterly convinced there's something under my clothes but again, nothing.