Part if a character body moving weirdly

[HudecP]

Dear community,

a part of my characters body starts always moving up and down (while walking), although it should not be moving on that place at all. I hope the problem is good to be seen on the photos. I would be grateful for any help. i can post more photos of the rig if necesseary. 

Many thanks in advance!

 

 

 

  

[alank99101739]

You could try putting sticks along the edge to reduce warping in that area...

[HudecP]

Well, that is something I've already tried. It helps a bit, but it doesn't really seem to be solving the problem...

[alank99101739]

Only other suggestion i have is to turn the yellow mesh of triangles on to see if you can work out the cause of the movement. (the icon at bottom under the character)