Hey! Thank you for playing the game! Yeah, from the first feedbacks, it seems that this part is too complicated... sorry. So, first, for the sneeze to work, the nose must be long (I forgot to mention this :-( ), then, you should hold the direction keys WHILE releasing 'x' (when you are still in the air). A force will throw you in the opposite direction to the keys (e.g. if you press down+right, you will go up+left). Hope this helped, don't hesitate to say if you need more explanations.
Cheers!