ahhh oh no he's trapped!
It's good practice to have ample room for your animations so you don't get any awkward boxed-in effects.
zanaril's edit has a nice back and forth wiggle which is really what this needs. I really can't recommend enough looking at what he did more closely. If a jelly moves in one direction, his jelliness will want to stay behind. It's all physics! Also up and down motion. As the jelly moves he gets all thin :c but than bounces back up before he goes to do another slide forward. c: