yea mine do the same thing. they like swerve their neck up like they r wolves howling and close their eyes liek they r swallowing soemthign big. Im pretty sure it is shedding. Frogs dotn have n e part of their body(such as finger nails opr claws) that can grab somethign thin and delicate(such as the skin here) so they move their body in wierd angles to like shake or rub it off. imagine urself being zipped up in a tight suit and u had no arms(pretend u did). U wud shake and squirm to rub or try to peel it off. Thats wat i think, mayb some more experienced owners can tell u more. Heh hope ur frog is doin something normal and not a sign showing a bad thing.
-----
3 Baby Whites Treefrog (Faygo, Fanta, Max)
1 Pacman (Big Mac)
3 Cats (Cindy, Rex, Tabby)
1 Mississippi Map Turtle (Lucky)
4 Fish (Was feeder for turtle but never ate them so now they big and family wit turtle.)
1 Parakeet (Swifty)