sudden drop in click cost

hello every one ;
i got a wear situation i got a new website the ctr was very very bad. after a little adjustments in the design the ctr raised significantly but unfortunately the click cost dropped to the ground. i am new to adsense. is it normal or maybe i am doing something wrong.
last thing i have in my account a website in other language than English which have a minimum click cost and very low earnings can this bad non-English website affect the other??
help me quickly as i am going mad

See original post by drahmedgalal