Dont wear 2 pairs of socks, the extra friction can actually cause more problems. 1 thick pair may help, but your best off taking them to where you got them fitted, and see if they can add anything to help the fit. To be honest it sounds like you got them a bit big to begin with. They should be pretty tight when new, and once they pack out, thats when they fit well. Yours sound like they were comfy straight away and now they have packed out there too big.
But overall take them to a bootfitter and see if anything can be done.