itchiness?

I don't know where else to ask this so I'm sorry in advance but it's a big issue for me. everytime I lay down to go to sleep recently I get insanely itchy, everywhere! and I can't sleep through the night, it's happened every so often before hand but now it's pretty much every night and I can't get any sleep. I am so exhausted and I just want to be able to fall asleep at a decent hour and stay asleep. and this only happens right as I go to bed, and I'll be wearing my pajamas a few hours before bed too, I just can't figure it out. does this happen to anyone else? how do you deal with it? does anyone have any suggestions?