the head bobbing animation needlessly introduces rolling (rotation along front-back axis) motion, which can be fine in isolated instances (such as tilting your head when peeking from cover) but can cause severe motion sickness in a head bob when it's inescapable and constant.

to disable the head bobbing animation, open console (ctrl+alt+`) and type:

cvaradd pm_nobob 1

try it out and see if it feels better.

to re-enable head bobbing, type:

cvaradd pm_nobob -1

to make it 'permanent', just right-click on the game in your steam library, select properties and in launch options add the same command:

+cvaradd pm_nobob 1

it will make the game execute this command every time it launches.

disabling head bobbing animation will interfere with scope and ADS on the bombenschuss.

in order to use the scope you'll have to re-enable bob. fortunately, you can bind a key to that. I use one of my mouse side buttons (mouse4) to toggle between enabling and disabling the head bobbing animation. type this in console (feel free to replace mouse4 with which ever key best suits your setup):

bind mouse4 toggle pm_nobob 1 0

now you can quickly re-enable bob in situations where you have to snipe a lot, which probably also means you're sitting behind cover and not running around a lot where it would cause motion sickness anyway.

this command does not need to be added to the launch options - game saves the bind automatically, you only need to enter it in the console once.