Oh goodness. Cold water my help with swelling so they can slide on off
^ there is a YouTube tutorial for that :)
You could also try the floss method. Where you thread the ring with the floss using whatever you can and then wrap the floss around you finger til your knuckle and then slide the ring off on top of the floss.
All I can think of is soap or butter. Or try running your hand under cold water and then try maybe?